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[bug#53878,RFC,8/9] gnu: Add chez-scheme-racket-variant.

Message ID 20220208151857.1900389-8-philip@philipmcgrath.com
State Accepted
Headers show
Series Update Racket to 8.4. Adjust Chez Scheme packages. | expand

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Commit Message

Philip McGrath Feb. 8, 2022, 3:18 p.m. UTC
The Racket variant of Chez Scheme can be used to support platforms that
are not yet supported by upstream Chez Scheme. The new function
'chez-scheme-for-system' selects the Chez Scheme package that best
supports the target system.

In the process, we also add packages for 'racket-vm-cgc',
'racket-vm-bc', and 'racket-vm-cs'. A future commit will change
'racket-minimal' to use the Racket VM implementation that best supports
the target system, as reported by 'racket-vm-for-system'.

* gnu/packages/patches/racket-enable-scheme-backport.patch: New patch.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/chez-and-racket-bootstrap.scm (racket-vm-cgc):
(racket-vm-bc):
(racket-vm-cs):
(chez-scheme-racket-variant-bootstrap-bootfiles):
(chez-scheme-racket-variant): New variables.
(chez-scheme-for-system, racket-vm-for-system): New exported functions.
* gnu/packages/loko.scm (loko-scheme): Use 'chez-scheme-for-system'.
* gnu/packages/emacs-xyz.scm (emacs-geiser-chez): Likewise
* gnu/packages/chez.scm (chez-srfi):
(chez-web):
(chez-sockets):
(chez-matchable):
(chez-irregex):
(chez-fmt):
(chez-mit):
(chez-scmutils): Likewise.
(chez-mit)[origin]<snippet>: Add workaround for Racket variant.
---
 gnu/local.mk                                  |   1 +
 gnu/packages/chez-and-racket-bootstrap.scm    | 512 +++++++++++++++++-
 gnu/packages/chez.scm                         |  40 +-
 gnu/packages/emacs-xyz.scm                    |   2 +-
 gnu/packages/loko.scm                         |   2 +-
 .../racket-enable-scheme-backport.patch       | 465 ++++++++++++++++
 6 files changed, 1003 insertions(+), 19 deletions(-)
 create mode 100644 gnu/packages/patches/racket-enable-scheme-backport.patch

Comments

Liliana Marie Prikler Feb. 9, 2022, 1:42 p.m. UTC | #1
Am Dienstag, dem 08.02.2022 um 10:18 -0500 schrieb Philip McGrath:
> The Racket variant of Chez Scheme can be used to support platforms
> that
> are not yet supported by upstream Chez Scheme. The new function
> 'chez-scheme-for-system' selects the Chez Scheme package that best
> supports the target system.
> 
> In the process, we also add packages for 'racket-vm-cgc',
> 'racket-vm-bc', and 'racket-vm-cs'. A future commit will change
> 'racket-minimal' to use the Racket VM implementation that best
> supports
> the target system, as reported by 'racket-vm-for-system'.
> 
> * gnu/packages/patches/racket-enable-scheme-backport.patch: New
> patch.
> * gnu/local.mk (dist_patch_DATA): Add it.
> * gnu/packages/chez-and-racket-bootstrap.scm (racket-vm-cgc):
> (racket-vm-bc):
> (racket-vm-cs):
> (chez-scheme-racket-variant-bootstrap-bootfiles):
> (chez-scheme-racket-variant): New variables.
> (chez-scheme-for-system, racket-vm-for-system): New exported
> functions.
> * gnu/packages/loko.scm (loko-scheme): Use 'chez-scheme-for-system'.
> * gnu/packages/emacs-xyz.scm (emacs-geiser-chez): Likewise
> * gnu/packages/chez.scm (chez-srfi):
> (chez-web):
> (chez-sockets):
> (chez-matchable):
> (chez-irregex):
> (chez-fmt):
> (chez-mit):
> (chez-scmutils): Likewise.
> (chez-mit)[origin]<snippet>: Add workaround for Racket variant.
This patch does a lot and should probably be separated into several
commits.  As far as the name "chez-scheme-racket-variant" is concerned,
I am not really a fan of it.  How would "chez-scheme-for-racket" sound?
Philip McGrath Feb. 10, 2022, 1:30 a.m. UTC | #2
Hi,

On 2/9/22 08:42, Liliana Marie Prikler wrote:
> Am Dienstag, dem 08.02.2022 um 10:18 -0500 schrieb Philip McGrath:
> This patch does a lot and should probably be separated into several
> commits.  As far as the name "chez-scheme-racket-variant" is concerned,
> I am not really a fan of it.  How would "chez-scheme-for-racket" sound?
> 

Thanks for taking a look!

Calling it "chez-scheme-for-racket" is fine with me---it's a little 
shorter, at least.

As far as splitting it up, yes, that makes sense. (There had at one 
point been some entanglements that I thought would make that difficult, 
but I've since fixed all those issues anyway.) What do you think of 
splitting it like this?

 >> * gnu/packages/patches/racket-enable-scheme-backport.patch: New
 >> patch.
 >> * gnu/local.mk (dist_patch_DATA): Add it.
 >> * gnu/packages/chez-and-racket-bootstrap.scm (racket-vm-cgc):
---
 >> (racket-vm-bc):
---
 >> (racket-vm-cs):
---
 >> (chez-scheme-racket-variant-bootstrap-bootfiles):
 >> (chez-scheme-racket-variant): New variables.
---
 >> (chez-scheme-for-system,
---
 >> (chez-mit)[origin]<snippet>: Add workaround for Racket variant.
---
 >> * gnu/packages/loko.scm (loko-scheme): Use 'chez-scheme-for-system'.
 >> * gnu/packages/emacs-xyz.scm (emacs-geiser-chez): Likewise
 >> * gnu/packages/chez.scm (chez-srfi):
 >> (chez-web):
 >> (chez-sockets):
 >> (chez-matchable):
 >> (chez-irregex):
 >> (chez-fmt):
 >> (chez-mit):
 >> (chez-scmutils): Likewise.
---
 >> racket-vm-for-system): New exported
 >> functions.

Alternatively, I could see adding the snippet to "chez-mit" in the same 
commit as changing it to use "chez-scheme-for-system", or I could split 
each changed package into its own commit (though those would be 
extremely small), or put the definition of "chez-scheme-for-system" 
together with its uses, or ...

Racket 8.4 was just released,[0] so I plan to send a revised series 
today or tomorrow.

-Philip

[0]: https://blog.racket-lang.org/2022/02/racket-v8-4.html
Liliana Marie Prikler Feb. 10, 2022, 7:08 a.m. UTC | #3
Hi,

Am Mittwoch, dem 09.02.2022 um 20:30 -0500 schrieb Philip McGrath:
> Calling it "chez-scheme-for-racket" is fine with me---it's a little 
> shorter, at least.
Okay.

> As far as splitting it up, yes, that makes sense. (There had at one 
> point been some entanglements that I thought would make that
> difficult, but I've since fixed all those issues anyway.) What do you
> think of splitting it like this?
I'm not entirely sure how the interdependencies are, but I'd do... 

>  >> * gnu/packages/patches/racket-enable-scheme-backport.patch: New
>  >> patch.
>  >> * gnu/local.mk (dist_patch_DATA): Add it.
>  >> * gnu/packages/chez-and-racket-bootstrap.scm (racket-vm-cgc):
> ---
>  >> (racket-vm-bc):
> ---
>  >> (racket-vm-cs):
> ---
>  >> (chez-scheme-for-racket-bootstrap-bootfiles):
>  >> (chez-scheme-for-racket): New variables.
These, then
>  >> (chez-mit)[origin]<snippet>: Add workaround for chez-scheme-for-
> racket.
then
> ---
>  >> (chez-scheme-for-system, racket-vm-for-system): New variables.
> ---
>  >> * gnu/packages/loko.scm (loko-scheme): Use 'chez-scheme-for-
> system'.
>  >> * gnu/packages/emacs-xyz.scm (emacs-geiser-chez): Likewise
>  >> * gnu/packages/chez.scm (chez-srfi):
>  >> (chez-web):
>  >> (chez-sockets):
>  >> (chez-matchable):
>  >> (chez-irregex):
>  >> (chez-fmt):
>  >> (chez-mit):
>  >> (chez-scmutils): Likewise.
> ---
If that's not possible, you can keep racket-vm-for-system as the final
patch.

> Racket 8.4 was just released,[0] so I plan to send a revised series 
> today or tomorrow.
Cool.

> [0]: https://blog.racket-lang.org/2022/02/racket-v8-4.html
diff mbox series

Patch

diff --git a/gnu/local.mk b/gnu/local.mk
index e3104fc0b6..94de782ca9 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1785,6 +1785,7 @@  dist_patch_DATA =						\
   %D%/packages/patches/ripperx-missing-file.patch		\
   %D%/packages/patches/rpcbind-CVE-2017-8779.patch		\
   %D%/packages/patches/rtags-separate-rct.patch			\
+  %D%/packages/patches/racket-enable-scheme-backport.patch	\
   %D%/packages/patches/racket-minimal-sh-via-rktio.patch	\
   %D%/packages/patches/remake-impure-dirs.patch			\
   %D%/packages/patches/restic-0.9.6-fix-tests-for-go1.15.patch	\
diff --git a/gnu/packages/chez-and-racket-bootstrap.scm b/gnu/packages/chez-and-racket-bootstrap.scm
index c6e4e07085..46da8e3ef2 100644
--- a/gnu/packages/chez-and-racket-bootstrap.scm
+++ b/gnu/packages/chez-and-racket-bootstrap.scm
@@ -34,15 +34,20 @@  (define-module (gnu packages chez-and-racket-bootstrap)
   #:use-module (guix build-system copy)
   #:use-module (guix build-system gnu)
   #:use-module (gnu packages)
+  #:use-module (gnu packages autotools)
+  #:use-module (gnu packages bash)
   #:use-module (gnu packages compression)
   #:use-module (gnu packages ghostscript)
+  #:use-module (gnu packages libffi)
   #:use-module (gnu packages linux)
   #:use-module (gnu packages ncurses)
   #:use-module (gnu packages netpbm)
   #:use-module (gnu packages tex)
   #:use-module (gnu packages xorg)
   #:use-module ((guix licenses)
-                #:prefix license:))
+                #:prefix license:)
+  #:export (chez-scheme-for-system
+            racket-vm-for-system))
 
 ;; Commentary:
 ;;
@@ -62,8 +67,164 @@  (define-module (gnu packages chez-and-racket-bootstrap)
 ;; Putting the relevant definitions together in this module avoids having to
 ;; work around dependency cycles.
 ;;
+;; Anatomy of Racket:
+;; ------------------
+;;
+;; The main Racket Git repository (<https://github.com/racket/racket>) is
+;; organized broadly like this:
+;;
+;;     .
+;;     ├── Makefile
+;;     ├── pkgs/
+;;     └── racket/
+;;         ├── collects/
+;;         └── src/
+;;             ├── configure
+;;             ├── Makefile.in
+;;             ├── bc/
+;;             ├── cs/
+;;             ├── ChezScheme/
+;;             └── ...
+;;
+;; The 'racket/src/' directory contains the source of the runtime system, core
+;; compiler, and primitives for the major Racket implementations: this layer
+;; is called the ``Racket VM''. It is basically a normal autotools
+;; project. (Even when Racket VM implementations use components implemented in
+;; Racket, they are compiled in special modes to produce VM primitives.)
+;; (There are or have been experimental Racket VM implementations elsewhere,
+;; e.g. <https://github.com/pycket/pycket>.) One way of thinking about the
+;; bounary between the Racket VM and Racket programs is that the VM implements
+;; the primitives accessed by the 'ffi/unsafe/vm' library. Another perspective
+;; is that DrRacket's ``Open defining file''/``Jump to definition'' features
+;; can navigate into Racket programs, including into the implementation of
+;; 'racket/base', but can not jump into the implementation of the Racket VM
+;; itself. A third, related perspective is that Racket code is usually
+;; installed with source files alongside compiled code (though this is not
+;; mandatory), whereas the Racket VM is installed only in compiled form.
+;;
+;; The 'racket/collects/' directory contains ``built in'' Racket libraries
+;; that are not part of any package, including the implementation of
+;; 'racket/base': in particular, it must contain enough to implement `raco pkg
+;; install'. It is theoretically possible to use the Racket VM layer without
+;; the main collections, but it is not stable or useful.
+;;
+;; The 'pkgs/' directory contains Racket packages that are especially closely
+;; tied to the implementation of the Racket VM, including 'compiler-lib',
+;; 'racket-doc', and 'racket-test'. Some of these packages depend on Racket
+;; packages that are developed in other Git repositories, predominantly but
+;; not exclusively under the 'racket' GitHub organization. Conversely, not all
+;; of the packages developed in the main Git repository are part of the main
+;; Racket distribution.  (Additionally, components of the Racket VM that are
+;; implemented in Racket can be installed as packages, mostly for ease of
+;; development.)
+;;
+;; The top-level 'Makefile' is more like a directory of scripts: it has
+;; convienience targets for developing Racket, and it cooperates with the
+;; 'distro-build' package to assemble custom Racket distributions. It is not
+;; part of Racket source distributions: the root of a source distribution is
+;; basically 'racket/src' with some extra package sources and configuration
+;; added.
+;;
+;; A ''minimal Racket'' installation includes two packages: 'base', which is a
+;; sort of bridge between the current ``built-in'' collections and the package
+;; system's model of dependencies, and 'racket-lib', which, for installations
+;; that can not rely on a system package manager, pulls in the SQLite and
+;; OpenSSL shared libraries as platform-specific dependencies for use by the
+;; ``built-in'' collections.
+;;
+;; The main Racket distribution consists of installing the 'main-distribution'
+;; package and all of its dependencies.
+;;
+;; The default mode when building Racket (or installing it with the released
+;; installers) is an ``in-place build'', which produces a self-contained,
+;; relocatable, roughly FHS-like directory. (Racket also supports
+;; ``Unix-style'' installations, which rearrange the parts of an in-place
+;; build into Racket-specific subdirectories and generally tries to work for
+;; installation into an FHS-based system.) Certain tools, e.g. 'distro-build'
+;; and 'raco cross', are able to work with an in-place Racket build.
+;;
+;; This file defines the packages 'racket-vm-cgc', 'racket-vm-bc', and
+;; 'racket-vm-cs'. All three are in-place builds of 'racket/src/' and
+;; 'racket/collects/' and are installed to 'opt/racket-vm/' in the store
+;; output. The function 'racket-vm-for-system' returns the recomended Racket
+;; VM package for a given system.
+;;
+;; The file 'racket.scm' builds on these packages to define 'racket-minimal'
+;; and 'racket' packages. These use Racket's support for ``layered
+;; installations'', which allow an immutable base layer to be extended with
+;; additional packages. The use the layer configuration directly provide
+;; ready-to-install FHS-like trees, rather than relying on the built in
+;; ``Unix-style install'' mechanism.
+;;
+;; Bootstrapping Racket:
+;; ---------------------
+;;
+;; Here's how bootstrapping Racket works:
+;;
+;;   - Racket BC [CGC] can be built with only a C compiler (except for
+;;     one caveat discussed below).
+;;   - Racket BC [3M] needs an existing Racket to run "xform",
+;;     which transforms its own C source code to add additional annotations
+;;     for the precise garbage collector.
+;;   - Racket CS needs (bootfiles for) Racket's fork of Chez Scheme.
+;;     It also needs an existing Racket to compile Racket-implemented
+;;     parts of the runtime system to R6RS libraries.
+;;   - Chez Scheme also needs bootfiles for itself, but Racket can simulate
+;;     enough of Chez Scheme to load Racket's fork of the Chez Scheme compiler
+;;     purely from source into Racket and apply the compiler to itself,
+;;     producing the needed bootfiles (albeit very slowly).
+;;     Any variant of Racket since version 7.1 can run the simulation.
+;;
+;; So, we build CGC to build 3M to build bootfiles and CS.
+;;
+;; (Note: since the CGC variant is basically only for bootstrapping, we
+;; often use "BC" to mean "3M", consistent with `(banner)` and the
+;; suffixes used on executables when more than one variant co-exists.)
+;;
+;; One remaining bootstrapping limitation is that Racket's reader, module
+;; system, and macro expander are implemented in Racket. For Racket CS,
+;; they are compiled to R6RS libraries as discussed above. This note from the
+;; README file applies to all such subsystems:
+;;
+;;     The Racket version must be practically the same as the current Racket
+;;     verson, although it can be the Racket BC implementation (instead of
+;;     the Racket CS implementation).
+;;
+;;     Unlike Chez Scheme boot files, the files generated in "schemified"
+;;     are human-readable and -editable Scheme code. That provides a way
+;;     out of bootstrapping black holes, even without BC.
+;;
+;; However, other Racket subsystems implemented in Racket for Racket CS
+;; use older C implementations for Racket BC, whereas the reader, expander,
+;; and module system were completely replaced with the Racket implementation
+;;
+;; For Racket BC, the compiled "linklet" s-expressions (primitive modules)
+;; are embeded in C as a static string constant. Eventually, they are further
+;; compiled by the C-implemented Racket BC bytecode and JIT compilers.
+;; (On platforms where Racket BC's JIT is not supported, yet another compiler
+;; instead compiles the linklets to C code, but this is not a bootstrapping
+;; issue.)
+;;
 ;; Code:
 
+(define* (chez-scheme-for-system #:optional
+                                 (system (or (%current-target-system)
+                                             (%current-system))))
+  "Return 'chez-scheme' if it supports SYSTEM without restrictions;
+'chez-scheme-racket-variant' otherwise."
+  (if (and=> (nix-system->chez-machine system)
+             chez-machine->upstream-restriction)
+      chez-scheme-racket-variant
+      chez-scheme))
+
+(define* (racket-vm-for-system #:optional
+                               (system (or (%current-target-system)
+                                           (%current-system))))
+  "Return 'racket-vm-cs' if it supports SYSTEM; 'racket-vm-bc' otherwise."
+  (if (nix-system->chez-machine system)
+      racket-vm-cs
+      racket-vm-bc))
+
 (define (chez-machine->unthreaded mach)
   "Given a string MACH naming a Chez Scheme machine type, returns a string
 naming the unthreaded machine type for the same architecture and OS as MACH.
@@ -189,19 +350,19 @@  (define* (nix-system->chez-machine #:optional (system (%current-system))
                 (chez-machine->threaded mach)))))))
 
 ;;
-;; Chez Scheme:
+;; Chez auxiliary G-expressions:
 ;;
 
 (define unbundle-chez-submodules
   #~(begin
       (use-modules (guix build utils))
       (for-each (lambda (dir)
-                (when (directory-exists? dir)
-                  (delete-file-recursively dir)))
-              '("stex"
-                "nanopass"
-                "lz4"
-                "zlib"))))
+                  (when (directory-exists? dir)
+                    (delete-file-recursively dir)))
+                '("stex"
+                  "nanopass"
+                  "lz4"
+                  "zlib"))))
 
 (define unpack-nanopass+stex
   #~(begin
@@ -216,6 +377,235 @@  (define unpack-nanopass+stex
           ;; otherwise, it will try to download submodules
           (display "# to placate ../configure")))))
 
+;;
+;; Racket VM:
+;;
+
+(define (racket-vm-common-configure-flags)
+  ;; under a lambda extraction to avoid evaluating bash-minimal too early
+  #~`(,@(cond
+         ((false-if-exception
+           (search-input-file %build-inputs "/bin/libtool"))
+          => (lambda (libtool)
+               (list (string-append "--enable-lt=" libtool))))
+         (else
+          '()))
+      ,@(cond
+         ((false-if-exception
+           (search-input-file %build-inputs "/opt/racket-vm/bin/racket"))
+          => (lambda (racket)
+               (list (string-append "--enable-racket=" racket))))
+         (else
+          '()))
+      ,(string-append "CPPFLAGS=-DGUIX_RKTIO_PATCH_BIN_SH="
+                      #$(file-append bash-minimal "/bin/sh"))
+      "--disable-strip"
+      "--enable-origtree"))
+
+(define-public racket-vm-cgc
+  ;; Eventually, it may make sense for some vm packages to not be hidden,
+  ;; but this one is especially likely to remain hidden.
+  (hidden-package
+   (package
+     (name "racket-vm-cgc")
+     (version "8.3.900")
+     ;; ^ Remember to also update the version of
+     ;;   chez-scheme-racket-variant-bootstrap-bootfiles
+     (source
+      (origin
+        (method git-fetch)
+        (uri (git-reference
+              (url "https://github.com/racket/racket")
+              ;;(commit (string-append "v" version))))
+              (commit "a8f2969753f70e70d73308250cae1d4eda087319")))
+        (sha256
+         (base32 "141c18wmvb6039cw87mvmm6xxs6k01wkcrxj0hfa1r8za25qa934"))
+        (file-name (git-file-name "racket" version))
+        (patches (search-patches "racket-minimal-sh-via-rktio.patch"
+                                 ;; Remove by Racket 8.5:
+                                 "racket-enable-scheme-backport.patch"))
+        (modules '((guix build utils)))
+        (snippet
+         #~(begin
+             ;; Unbundle Chez submodules.
+             (with-directory-excursion "racket/src/ChezScheme"
+               #$unbundle-chez-submodules)
+             ;; Unbundle libffi.
+             (delete-file-recursively "racket/src/bc/foreign/libffi")))))
+     (inputs (list ncurses ;; <- common to all variants (for #%terminal)
+                   bash-minimal ;; <- common to all variants (for `system`)
+                   libffi)) ;; <- only for BC variants
+     (native-inputs (list libtool)) ;; <- only for BC variants
+     (outputs '("out" "debug"))
+     (build-system gnu-build-system)
+     (arguments
+      (list
+       #:configure-flags
+       #~(cons "--enable-cgcdefault"
+               #$(racket-vm-common-configure-flags))
+       ;; Tests are in packages like racket-test-core and
+       ;; main-distribution-test that aren't part of the main
+       ;; distribution.
+       #:tests? #f
+       ;; Upstream recommends #:out-of-source?, and it does
+       ;; help with debugging, but it confuses `install-license-files`.
+       #:modules '((ice-9 match)
+                   (ice-9 regex)
+                   (guix build gnu-build-system)
+                   (guix build utils))
+       #:strip-directories #~'("opt/racket-vm/bin"
+                               "opt/racket-vm/lib")
+       #:phases
+       #~(let ()
+           (define* ((wrap-racket-vm-outputs phase) . args)
+             (apply
+              phase
+              (let loop ((args args))
+                (match args
+                  ((#:outputs outputs . args)
+                   `(#:outputs
+                     ,(let loop ((outputs outputs))
+                        (match outputs
+                          ((("out" . out) . outputs)
+                           `(("out" . ,(string-append out "/opt/racket-vm/"))
+                             ,@outputs))
+                          ((other . outputs)
+                           (cons other (loop outputs)))))
+                     ,@args))
+                  ((arg . args)
+                   (cons arg (loop args)))))))
+           (modify-phases %standard-phases
+             (add-before 'configure 'initialize-config.rktd
+               (lambda* (#:key inputs #:allow-other-keys)
+                 (define (write-racket-hash alist)
+                   ;; inside must use dotted pair notation
+                   (display "#hash(")
+                   (for-each (match-lambda
+                               ((k . v)
+                                (format #t "(~s . ~s)" k v)))
+                             alist)
+                   (display ")\n"))
+                 (define maybe-release-catalog
+                   (let ((v #$(package-version this-package)))
+                     (if (string-match "^[0-9]+\\.[0-9]+($|\\.[0-8][0-9]*$)"
+                                       v)
+                         `(,(string-append
+                             "https://download.racket-lang.org/releases/"
+                             v
+                             "/catalog/"))
+                         '())))
+                 (mkdir-p "racket/etc")
+                 (with-output-to-file "racket/etc/config.rktd"
+                   (lambda ()
+                     (write-racket-hash
+                      `((build-stamp . "")
+                        (catalogs ,@maybe-release-catalog
+                                  #f)))))))
+             (add-before 'configure 'chdir
+               (lambda _
+                 (chdir "racket/src")))
+             (replace 'configure
+               (wrap-racket-vm-outputs
+                (assoc-ref %standard-phases 'configure)))
+             (replace 'patch-shebangs
+               (wrap-racket-vm-outputs
+                (assoc-ref %standard-phases 'patch-shebangs)))
+             (replace 'validate-runpath
+               (wrap-racket-vm-outputs
+                (assoc-ref %standard-phases 'validate-runpath)))
+             (replace 'make-dynamic-linker-cache
+               (wrap-racket-vm-outputs
+                (assoc-ref %standard-phases 'make-dynamic-linker-cache)))
+             (replace 'patch-dot-desktop-files
+               (wrap-racket-vm-outputs
+                (assoc-ref %standard-phases 'patch-dot-desktop-files)))))))
+     (home-page "https://racket-lang.org")
+     (synopsis "Old Racket implementation used for bootstrapping")
+     (description "This variant of the Racket BC (``before Chez'' or
+``bytecode'') implementation is not recommended for general use.  It uses
+CGC (a ``Conservative Garbage Collector''), which was succeeded as default in
+PLT Scheme version 370 (which translates to 3.7 in the current versioning
+scheme) by the 3M variant, which in turn was succeeded in version 8.0 by the
+Racket CS implementation.
+
+Racket CGC is primarily used for bootstrapping Racket BC [3M].  It may
+also be used for embedding applications without the annotations needed in C
+code to use the 3M garbage collector.")
+     ;; https://download.racket-lang.org/license.html
+     ;; The LGPL components are only used by Racket BC.
+     (license (list license:lgpl3+ license:asl2.0 license:expat)))))
+
+(define-public racket-vm-bc
+  (package
+    (inherit racket-vm-cgc)
+    (name "racket-vm-bc")
+    (native-inputs
+     (modify-inputs (package-native-inputs racket-vm-cgc)
+       (prepend racket-vm-cgc)))
+    (arguments
+     (substitute-keyword-arguments (package-arguments racket-vm-cgc)
+       ((#:configure-flags _ '())
+        #~(cons "--enable-bconly"
+                #$(racket-vm-common-configure-flags)))))
+    (synopsis "Racket BC [3M] implementation")
+    (description "The Racket BC (``before Chez'' or ``bytecode'')
+implementation was the default before Racket 8.0.  It uses a compiler written
+in C targeting architecture-independent bytecode, plus a JIT compiler on most
+platforms.  Racket BC has a different C API and supports a slightly different
+set of architectures than the current default runtime system, Racket CS (based
+on ``Chez Scheme'').  It is the recommended implementation for architectures
+that Racket CS doesn't support.
+
+This package is the normal implementation of Racket BC with a precise garbage
+collector, 3M (``Moving Memory Manager'').")))
+
+(define-public racket-vm-cs
+  (package
+    (inherit racket-vm-bc)
+    (name "racket-vm-cs")
+    (inputs
+     (modify-inputs (package-inputs racket-vm-cgc)
+       (prepend zlib lz4)
+       (delete "libffi")))
+    (native-inputs
+     (modify-inputs (package-native-inputs racket-vm-cgc)
+       (delete "libtool")
+       (prepend chez-scheme-racket-variant
+                chez-nanopass-bootstrap
+                racket-vm-bc)))
+    (arguments
+     (substitute-keyword-arguments (package-arguments racket-vm-cgc)
+       ((#:phases those-phases #~%standard-phases)
+        #~(modify-phases #$those-phases
+            (add-after 'unpack 'unpack-nanopass+stex
+              (lambda args
+                (with-directory-excursion "racket/src/ChezScheme"
+                  #$unpack-nanopass+stex)))))
+       ((#:configure-flags _ '())
+        #~(cons* "--enable-csonly"
+                 "--enable-libz"
+                 "--enable-lz4"
+                 (string-append "--enable-scheme="
+                                #$(this-package-native-input
+                                   "chez-scheme-racket-variant")
+                                "/bin/scheme")
+                 #$(racket-vm-common-configure-flags)))))
+    (synopsis "Racket CS implementation")
+    (description "The Racket CS implementation, which uses ``Chez Scheme'' as
+its core compiler and runtime system, has been the default Racket VM
+implemetation since Racket 8.0.  It performs better than the Racket BC
+implementation for most programs.
+
+Using the Racket VM packages directly is not recommended: instead, install the
+@code{racket-minimal} or @code{racket} packages.")
+    ;; https://download.racket-lang.org/license.html
+    ;; The LGPL components are only used by Racket BC.
+    (license (list license:asl2.0 license:expat))))
+
+;;
+;; Chez Scheme:
+;;
+
 (define-public chez-scheme-bootstrap-bootfiles
   (package
     (name "chez-scheme-bootstrap-bootfiles")
@@ -401,6 +791,112 @@  (define* (stex-make #:optional (suffix ""))
 and 32-bit PowerPC architectures.")
     (license license:asl2.0)))
 
+
+(define-public chez-scheme-racket-variant-bootstrap-bootfiles
+  (package
+    (inherit chez-scheme-bootstrap-bootfiles)
+    (name "chez-scheme-racket-variant-bootstrap-bootfiles")
+    (version "9.5.7.3")
+    ;; The version should match `(scheme-fork-version-number)`.
+    ;; See racket/src/ChezScheme/s/cmacros.ss c. line 360.
+    ;; It will always be different than the upstream version!
+    (source (package-source racket-vm-cgc))
+    (native-inputs (list chez-nanopass-bootstrap racket-vm-bc))
+    (arguments
+     (substitute-keyword-arguments
+         (package-arguments chez-scheme-bootstrap-bootfiles)
+       ((#:phases those-phases #~%standard-phases)
+        #~(modify-phases #$those-phases
+            (add-after 'unpack 'chdir
+              (lambda args
+                (chdir "racket/src/ChezScheme")))
+            (add-after 'chdir 'unpack-nanopass+stex
+              (lambda args
+                #$unpack-nanopass+stex))
+            (add-before 'install 'build
+              (lambda* (#:key native-inputs inputs #:allow-other-keys)
+                (invoke (search-input-file (or native-inputs inputs)
+                                           "/opt/racket-vm/bin/racket")
+                        "rktboot/main.rkt")))))))
+    (home-page "https://github.com/racket/ChezScheme")
+    ;; ^ This is downstream of https://github.com/racket/racket,
+    ;; but it's designed to be a friendly landing place for people
+    ;; who want a ChezScheme-shaped repositroy.
+    (synopsis "Chez Scheme bootfiles bootstrapped by Racket")
+    (description "Chez Scheme is a self-hosting compiler: building it
+requires ``bootfiles'' containing the Scheme-implemented portions compiled for
+the current platform.  (Chez can then cross-compile bootfiles for all other
+supported platforms.)
+
+The Racket package @code{cs-bootstrap} (part of the main Racket Git
+repository) implements enough of a Chez Scheme simulation to load the Chez
+Scheme compiler purely from source into Racket and apply the compiler to
+itself, thus bootstrapping Chez Scheme.  Bootstrapping takes about 10 times as
+long as using an existing Chez Scheme, but @code{cs-bootstrap} supports Racket
+7.1 and later, including the Racket BC variant.
+
+Note that the generated bootfiles are specific to Racket's fork of Chez
+Scheme, and @code{cs-bootstrap} does not currently support building upstream
+Chez Scheme.")
+    (properties `())
+    (license license:asl2.0)))
+
+(define-public chez-scheme-racket-variant
+  (package
+    (inherit chez-scheme)
+    (name "chez-scheme-racket-variant")
+    (version (package-version chez-scheme-racket-variant-bootstrap-bootfiles))
+    (source (package-source racket-vm-cgc))
+    (inputs
+     (modify-inputs (package-inputs chez-scheme)
+       (delete "libx11" "util-linux:lib")))
+    (native-inputs
+     (modify-inputs (package-native-inputs chez-scheme)
+       (replace "chez-scheme-bootstrap-bootfiles"
+         chez-scheme-racket-variant-bootstrap-bootfiles)))
+    (arguments
+     (substitute-keyword-arguments (package-arguments chez-scheme)
+       ((#:configure-flags cfg-flags #~'())
+        #~(cons "--disable-x11" #$cfg-flags))
+       ((#:phases those-phases #~%standard-phases)
+        #~(modify-phases #$those-phases
+            (add-after 'unpack 'chdir
+              (lambda args
+                (chdir "racket/src/ChezScheme")))))))
+    (supported-systems (filter nix-system->chez-machine
+                               %supported-systems))
+    (home-page
+     (package-home-page chez-scheme-racket-variant-bootstrap-bootfiles))
+    (synopsis "Variant of Chez Scheme extended for Racket")
+    (description "This variant of Chez Scheme is extended to support the
+implementation of Racket.  It may be useful on platforms that are not yet
+supported by upstream Chez Scheme.
+
+Main additions to Chez Scheme in the Racket variant:
+@itemize @bullet
+@item
+AArch64 support
+@item
+Portable bytes (@code{pb}) support, which is mainly useful for bootstrapping
+a build on any supported platform
+@item
+Unboxed floating-point arithmetic and flvectors
+@item
+Type reconstruction during optimization (especially for safe code)
+@item
+Continuation attachments
+@item
+Parallel garbage collection, in-place garbage collection for old-generation
+objects (instead of always copying), and reachability-based memory
+accounting
+@item
+Ordered finalization, immobile (but collectable) objects, weak/ephemeron
+generic hash tables, and reference bytevectors
+@item
+Faster multiplication and division for large exact numbers
+@end itemize")
+    (license license:asl2.0)))
+
 ;;
 ;; Chez's bootstrap dependencies:
 ;;
diff --git a/gnu/packages/chez.scm b/gnu/packages/chez.scm
index 54bbee7923..aa8c305d72 100644
--- a/gnu/packages/chez.scm
+++ b/gnu/packages/chez.scm
@@ -74,7 +74,7 @@  (define-public chez-srfi
        (file-name (git-file-name name version))))
     (build-system gnu-build-system)
     (native-inputs
-     (list chez-scheme))
+     (list (chez-scheme-for-system)))
     (arguments
      (list #:make-flags (chez-make-flags name version)
            #:test-target "test"
@@ -105,7 +105,7 @@  (define-public chez-web
           (base32 "1dq25qygyncbfq4kwwqqgyyakfqjwhp5q23vrf3bff1p66nyfl3b"))))
       (build-system gnu-build-system)
       (native-inputs
-       (list chez-scheme
+       (list (chez-scheme-for-system)
              ghostscript
              ;; FIXME: This package fails to build with the error:
              ;;     mktexpk: don't know how to create bitmap font for bchr8r
@@ -170,7 +170,7 @@  (define-public chez-sockets
           (base32 "1n5fbwwz51fdzvjackgmnsgh363g9inyxv7kmzi0469cwavwcx5m"))))
       (build-system gnu-build-system)
       (native-inputs
-       (list chez-scheme
+       (list (chez-scheme-for-system)
              chez-web
              (texlive-updmap.cfg (list texlive-pdftex))))
       (arguments
@@ -256,7 +256,7 @@  (define-public chez-matchable
     (inputs
      (list chez-srfi)) ; for tests
     (native-inputs
-     (list chez-scheme))
+     (list (chez-scheme-for-system)))
     (arguments
      (list #:make-flags (chez-make-flags name version)
            #:test-target "test"
@@ -288,7 +288,7 @@  (define-public chez-irregex
     (propagated-inputs
      (list chez-srfi)) ; for irregex-utils
     (native-inputs
-     (list chez-scheme))
+     (list (chez-scheme-for-system)))
     (arguments
      (list #:make-flags (chez-make-flags name version)
            #:test-target "test"
@@ -319,7 +319,7 @@  (define-public chez-fmt
     (propagated-inputs
      (list chez-srfi)) ; for irregex-utils
     (native-inputs
-     (list chez-scheme))
+     (list (chez-scheme-for-system)))
     (arguments
      (list #:make-flags (chez-make-flags name version)
            #:test-target "chez-check"
@@ -355,12 +355,34 @@  (define-public chez-mit
              (commit (string-append "v" version))))
        (sha256
         (base32 "0c7i3b6i90xk96nmxn1pc9272a4yal4v40dm1a4ybdi87x53zkk0"))
-       (file-name (git-file-name name version))))
+       (file-name (git-file-name name version))
+       (snippet
+        ;; Workaround for chez-scheme-racket-variant.
+        ;; See: https://github.com/racket/racket/issues/4151
+        #~(begin
+            (use-modules (guix build utils))
+            (substitute* "mit/core.sls"
+              (("[(]import ")
+               "(import (only (chezscheme) import)\n")
+              (("[(]define string->uninterned-symbol gensym[)]")
+               (format #f "~s"
+                       '(begin
+                          (import (only (chezscheme)
+                                        meta-cond
+                                        library-exports))
+                          (meta-cond
+                           ((memq 'string->uninterned-symbol
+                                  (library-exports '(chezscheme)))
+                            (import (only (chezscheme)
+                                          string->uninterned-symbol)))
+                           (else
+                            (define string->uninterned-symbol
+                              gensym)))))))))))
     (build-system gnu-build-system)
     (inputs
      (list chez-srfi))       ; for tests
     (native-inputs
-     (list chez-scheme))
+     (list (chez-scheme-for-system)))
     (arguments
      (list #:make-flags (chez-make-flags name version)
            #:test-target "test"
@@ -391,7 +413,7 @@  (define-public chez-scmutils
     (inputs
      (list chez-srfi))       ; for tests
     (native-inputs
-     (list chez-scheme))
+     (list (chez-scheme-for-system)))
     (propagated-inputs
      (list chez-mit chez-srfi))
     (arguments
diff --git a/gnu/packages/emacs-xyz.scm b/gnu/packages/emacs-xyz.scm
index c6a62e8767..54774d9cad 100644
--- a/gnu/packages/emacs-xyz.scm
+++ b/gnu/packages/emacs-xyz.scm
@@ -451,7 +451,7 @@  (define-public emacs-geiser-chez
                 (string-append
                  "(eval-after-load 'geiser-impl '" all ")"))))))))
     (inputs
-     (list chez-scheme))
+     (list (chez-scheme-for-system)))
     (propagated-inputs
      (list emacs-geiser))
     (home-page "https://nongnu.org/geiser/")
diff --git a/gnu/packages/loko.scm b/gnu/packages/loko.scm
index 74a649b8a1..a7ab12a0c4 100644
--- a/gnu/packages/loko.scm
+++ b/gnu/packages/loko.scm
@@ -71,7 +71,7 @@  (define-public loko-scheme
              #t)))))
     (native-inputs
      `(("akku" ,akku)
-       ("chez-scheme" ,chez-scheme)
+       ("chez-scheme" ,(chez-scheme-for-system))
        ("struct" ,guile-struct-pack)
        ("laesare" ,guile-laesare)
        ("pfds" ,guile-pfds)
diff --git a/gnu/packages/patches/racket-enable-scheme-backport.patch b/gnu/packages/patches/racket-enable-scheme-backport.patch
new file mode 100644
index 0000000000..3a5a4a3d82
--- /dev/null
+++ b/gnu/packages/patches/racket-enable-scheme-backport.patch
@@ -0,0 +1,465 @@ 
+From 8d7687842f099e3e7e60d3a83fed58b2c6a92863 Mon Sep 17 00:00:00 2001
+From: Matthew Flatt <mflatt@racket-lang.org>
+Date: Sun, 6 Feb 2022 10:36:09 -0700
+Subject: [PATCH 1/2] Chez Scheme: adapt bootfile build for supplied `Scheme=`
+
+(cherry picked from commit fca1e02349664060e10278ca2ce6577a949bebf5)
+
+(Fixed conflicts by dropping pbchunks and pbarch changes.)
+---
+ racket/src/ChezScheme/configure  | 15 ++++++++++++++-
+ racket/src/ChezScheme/s/Mf-base  |  4 ++--
+ racket/src/ChezScheme/s/Mf-cross |  4 +++-
+ 3 files changed, 19 insertions(+), 4 deletions(-)
+
+diff --git a/racket/src/ChezScheme/configure b/racket/src/ChezScheme/configure
+index 4515ffc105..0098829091 100755
+--- a/racket/src/ChezScheme/configure
++++ b/racket/src/ChezScheme/configure
+@@ -45,6 +45,7 @@ threads=yes
+ nothreads=no
+ temproot=""
+ help=no
++forceworkarea=no
+ gzipmanpages=yes
+ installowner=""
+ installgroup=""
+@@ -205,6 +206,9 @@ while [ $# != 0 ] ; do
+     --pb)
+       pb=yes
+       ;;
++    --force)
++      forceworkarea=yes
++      ;;
+     --installprefix=*)
+       installprefix=`echo $1 | sed -e 's/^--installprefix=//'`
+       ;;
+@@ -439,6 +443,7 @@ if [ "$help" = "yes" ]; then
+   echo "  --toolprefix=<prefix>             prefix tool (compiler, linker, ...) names"
+   echo "  --[no]gzip-man-pages              compress manual pages ($gzipmanpages)"
+   echo "  --workarea=<pathname>             build directory ($w)"
++  echo "  --force                           configure even without boot files"
+   echo "  CC=<C compiler>                   C compiler"
+   echo "  CPPFLAGS=<C preprocessor flags>   C preprocessor flags"
+   echo "  CFLAGS=<C compiler flags>         C compiler flags"
+@@ -721,8 +726,16 @@ case "${flagsmuni}" in
+         ;;
+ esac
+ 
++if [ "$w" = "$m" ] ; then
++    configuringin=""
++else
++    configuringin=" in $w"
++fi
++
+ if [ -f boot/$m/scheme.boot -o -f "$srcdir"/boot/$m/scheme.boot ] ; then
+-  echo "Configuring for $m"
++    echo "Configuring for $m$configuringin"
++elif [ "$forceworkarea" = yes ] ; then
++    echo "Configuring for $m$configuringin despite missing boot files"
+ else
+   if [ "$m" = "" ] ; then
+       maybem="<machine type>"
+diff --git a/racket/src/ChezScheme/s/Mf-base b/racket/src/ChezScheme/s/Mf-base
+index cc6178c973..1f4a967998 100644
+--- a/racket/src/ChezScheme/s/Mf-base
++++ b/racket/src/ChezScheme/s/Mf-base
+@@ -94,7 +94,7 @@ endif
+ # that Scheme and SCHEMEHEAPDIRS are set by Mf-cross to point to the host Scheme
+ # implementation
+ Scheme = ../bin/$m/scheme${ExeSuffix}
+-export SCHEMEHEAPDIRS=../boot/%m
++export SCHEMEHEAPDIRS=../boot/$m
+ export CHEZSCHEMELIBDIRS=.
+ 
+ # Define the libdirs separator character
+@@ -691,4 +691,4 @@ reset-one:
+ 
+ .PHONY: run
+ run:
+-	env SCHEMEHEAPDIRS=../boot/$m/ ../bin/$m/scheme $(ARGS)
++	env SCHEMEHEAPDIRS=${SCHEMEHEAPDIRS} ${Scheme} $(ARGS)
+diff --git a/racket/src/ChezScheme/s/Mf-cross b/racket/src/ChezScheme/s/Mf-cross
+index d796cbb459..397af59a28 100644
+--- a/racket/src/ChezScheme/s/Mf-cross
++++ b/racket/src/ChezScheme/s/Mf-cross
+@@ -43,5 +43,7 @@ x$(xm).$(m):
+ 	$(MAKE) -f Mf-cross m=$(m) xm=$(xm) i=f o=3 d=0 xpatch
+ 	mv xpatch x$(xm).$(m)
+ 
++ifneq ($(SCHEMEHEAPDIRS),:)
+ # Ensure that cross-compiling "nanopass.so" is rebuilt if the host compiler changed
+-nanopass.so: ${SCHEME} ${SCHEMEHEAPDIRS}/petite.boot ${SCHEMEHEAPDIRS}/scheme.boot
++nanopass.so: ${Scheme} ${SCHEMEHEAPDIRS}/petite.boot ${SCHEMEHEAPDIRS}/scheme.boot
++endif
+-- 
+2.32.0
+
+
+From 26c8e2c1d9b02ad85acef8bda40d92154cf0b699 Mon Sep 17 00:00:00 2001
+From: Matthew Flatt <mflatt@racket-lang.org>
+Date: Sun, 6 Feb 2022 11:03:30 -0700
+Subject: [PATCH 2/2] configure: make `--enable-scheme` work with an executable
+
+When the same Chez Scheme version as used by Racket is already
+available, then `--enable-scheme=...` can supply an executable. For
+cross builds, `--enable-scheme=...` can still supply a build
+directory, instead, as before.
+
+(cherry picked from commit 4f0e76855ce7e86107de495292a553469daf0b3f)
+---
+ racket/src/ChezScheme/makefiles/Makefile.in |  3 ++
+ racket/src/README.txt                       | 30 +++++++++++---
+ racket/src/configure                        |  8 +++-
+ racket/src/cs/README.txt                    |  6 ++-
+ racket/src/cs/c/Makefile.in                 | 44 ++++++++++++++++-----
+ racket/src/cs/c/configure                   | 24 +++++++++--
+ racket/src/cs/c/configure.ac                | 21 ++++++++--
+ 7 files changed, 112 insertions(+), 24 deletions(-)
+
+diff --git a/racket/src/ChezScheme/makefiles/Makefile.in b/racket/src/ChezScheme/makefiles/Makefile.in
+index c396efc851..3998ef9ccd 100644
+--- a/racket/src/ChezScheme/makefiles/Makefile.in
++++ b/racket/src/ChezScheme/makefiles/Makefile.in
+@@ -59,6 +59,9 @@ reset:
+ %.boot:
+ 	(cd $(workarea) && $(MAKE) $*.boot)
+ 
++auto.boot:
++	(cd $(workarea) && $(MAKE) $(defaultm).boot)
++
+ # <machine>.bootquick to build boot files for <machine>
+ # with o=3 d=0 for the cross compiler, and only after
+ # building the kernel for the configured machine
+diff --git a/racket/src/README.txt b/racket/src/README.txt
+index 98647aebce..d77310b4a4 100644
+--- a/racket/src/README.txt
++++ b/racket/src/README.txt
+@@ -354,6 +354,10 @@ variant of MinGW without "libdelayimp.a", get the implementation of
+ ========================================================================
+ 
+ Cross-compilation requires at least two flags to `configure`:
++`--host=OS` and either `--enable-racket=RACKET` or (for Racket CS)
++`--enable-scheme-SCHEME`.
++
++More information:
+ 
+  * `--host=OS`, where OS is something like `i386-gnu-linux` to
+    indicate the target platform.
+@@ -374,11 +378,27 @@ Cross-compilation requires at least two flags to `configure`:
+    run `configure` again (with no arguments) in a "local" subdirectory
+    to create a build for the current platform.
+ 
+-An additional flag is needed for building Racket CS, unless the flag
+-`--enable-racket=auto` is used:
+-
+- * `--enable-scheme=DIR`, where DIR is a path that has a "ChezScheme"
+-   directory where Chez Scheme is built for the host system.
++ * `--enable-scheme=SCHEME`, where SCHEME is a Chez Scheme executable
++   executable that runs on the build platform; the executable must be
++   the same version as used in Racket built for the target platform.
++ 
++   Supplying `--enable-scheme=DIR` is also supported in cross-build
++   mode, where DIR is a path that has a "ChezScheme" directory where
++   Chez Scheme is built for the host system.
++
++The `--enable-racket=RACKET` and `--enable-scheme=SCHEME` flags are
++allowed for non-cross builds, too:
++
++ * For Racket CS, supplying either selects a Racket or Chez Scheme
++   implementation used to create boot files to the build platform.
++   Suppling Chez Scheme is a much more direct path, but when Racket is
++   supplied, its version does not have to match the version being
++   built.
++
++ * For Racket BC, `--enable-racket=RACKET` selects a Racket for
++   prepare C sources to cooperate with garbage collection. Its version
++   needs to be close to the one being built, and potentially exactly
++   the same version.
+ 
+ Some less commonly needed `configure` flags are for Racket BC:
+ 
+diff --git a/racket/src/configure b/racket/src/configure
+index c9f3ba4419..1b53ec7ce2 100755
+--- a/racket/src/configure
++++ b/racket/src/configure
+@@ -9,6 +9,7 @@ pb_dir="$dir/ChezScheme/boot/pb"
+ use_cs=maybe
+ use_bc=maybe
+ supplied_racket=no
++supplied_scheme=no
+ enable_boothelp=
+ 
+ # We don't have to detect conflicts like `--enable-csdefault --enable-bcdefault`,
+@@ -34,6 +35,9 @@ for arg in $*; do
+         --enable-racket=*)
+             supplied_racket=yes
+             ;;
++        --enable-scheme=*)
++            supplied_scheme=yes
++            ;;
+         --help | -h)
+             echo $0:
+             echo see --help-bc or --help-cs, since the Racket CS build and the
+@@ -70,8 +74,8 @@ elif test "$use_cs" = "maybe" ; then
+ fi
+ 
+ if test "$use_cs" = "yes" ; then
+-    if test $use_bc = no  -a $supplied_racket = no -a ! -d "$pb_dir" ; then
+-        echo $0: must have $pb_dir or --enable-racket=... for --enable-csonly
++    if test $use_bc = no  -a $supplied_racket = no  -a $supplied_scheme = no  -a ! -d "$pb_dir" ; then
++        echo $0: must have $pb_dir, --enable-racket=... or --enable-scheme=... for --enable-csonly
+         exit 1
+     fi
+ 
+diff --git a/racket/src/cs/README.txt b/racket/src/cs/README.txt
+index 2ece417b78..8e6fc57b74 100644
+--- a/racket/src/cs/README.txt
++++ b/racket/src/cs/README.txt
+@@ -39,6 +39,11 @@ build:
+    installed in the "../ChezScheme/boot/pb" directory as described by
+    "../ChezScheme/BUILDING".
+ 
++   Supplying `--enable-scheme=...` is also an option if you alerady
++   have the same version of Chez Scheme built on the current platform.
++   Another build will be created, anyway, but more quickly than
++   without Chez Scheme.
++
+  * Racket is needed to generate the files in the "schemified"
+    directory from the sources in sibling directories like "../io". The
+    Racket version must be practically the same as the current Racket
+@@ -48,7 +53,6 @@ build:
+    Unlike Chez Scheme boot files, the files generated in "schemified"
+    are human-readable and -editable Scheme code. That provides a way
+    out of bootstrapping black holes, even without BC.
+-   
+ 
+ 
+ ========================================================================
+diff --git a/racket/src/cs/c/Makefile.in b/racket/src/cs/c/Makefile.in
+index 54a644a1d9..d73993f0fc 100644
+--- a/racket/src/cs/c/Makefile.in
++++ b/racket/src/cs/c/Makefile.in
+@@ -12,7 +12,9 @@ CS_HOST_WORKAREA_PREFIX = @CS_HOST_WORKAREA_PREFIX@
+ SCHEME_HOST_WORKAREA = $(CS_HOST_WORKAREA_PREFIX)$(SCHEME_WORKAREA)
+ SCHEME_BIN = $(SCHEME_HOST_WORKAREA)/$(MACH)/bin/$(MACH)/scheme
+ SCHEME_INC = $(SCHEME_HOST_WORKAREA)/$(MACH)/boot/$(MACH)
+-SCHEME = $(SCHEME_BIN) -B $(SCHEME_INC)/petite.boot -B $(SCHEME_INC)/scheme.boot
++SCHEME_built = $(SCHEME_BIN) -B $(SCHEME_INC)/petite.boot -B $(SCHEME_INC)/scheme.boot
++SCHEME_existing = @MAKE_SCHEME_SCHEME@
++SCHEME = $(SCHEME@USE_SCHEME_MODE@)
+ 
+ TARGET_MACH = @TARGET_MACH@
+ SCHEME_TARGET_INC = $(SCHEME_WORKAREA)/$(TARGET_MACH)/boot/$(TARGET_MACH)
+@@ -88,7 +90,7 @@ mainsrcdir = @srcdir@/../..
+ @INCLUDEDEP@ @srcdir@/../../version/version.mak
+ 
+ cs:
+-	$(MAKE) scheme@T_CROSS_MODE@
++	$(MAKE) scheme@MAKE_SCHEME_MODE@
+ 	$(MAKE) racket-so
+ 	cd rktio; $(MAKE)
+ 	$(MAKE) racketcs
+@@ -121,9 +123,13 @@ racket-so:
+ 
+ RACKET_SO_ENV = @CONFIGURE_RACKET_SO_COMPILE@
+ 
++TARGET_MACH_built = $(TARGET_MACH)
++TARGET_MACH_existing = xc-$(TARGET_MACH)
++XPATCH_FILE = $(SCHEME_WORKAREA)/$(TARGET_MACH@USE_SCHEME_MODE@)/s/xpatch
++
+ CS_PROGS = SCHEME="$(SCHEME)"
+ CS_OPTS = COMPRESS_COMP=@COMPRESS_COMP@ @ENABLE_OR_DISABLE_WPO@
+-CS_OPTScross = $(CS_OPTS) CSO=$(MACH) CROSS_COMP="--xpatch $(SCHEME_WORKAREA)/$(TARGET_MACH)/s/xpatch"
++CS_OPTScross = $(CS_OPTS) CSO=$(MACH) CROSS_COMP="--xpatch $(XPATCH_FILE)"
+ PASS_COMPILE_DEPS = EXTRA_COMPILE_DEPS="$(SCHEME_INC)/petite.boot $(SCHEME_INC)/scheme.boot"
+ 
+ build-racket-so:
+@@ -163,6 +169,15 @@ pb-bootquick:
+ 	cd $(SCHEME_WORKAREA) && $(MAKE) reset
+ 	$(SHELL) $(srcdir)/ready_boot.sh $(MACH) $(SCHEME_WORKAREA)
+ 
++scheme-via-scheme:
++	$(MAKE) $(SCHEME_WORKAREA)/boot/$(MACH)/scheme.boot
++	$(MAKE) mach-make
++
++$(SCHEME_WORKAREA)/boot/$(MACH)/scheme.boot:
++	mkdir -p $(SCHEME_WORKAREA)
++	$(MAKE) config-scheme CONFIG_SCHEME_MODE="$(CONFIG_SCHEME_MODE) --force"
++	cd $(SCHEME_WORKAREA) && $(MAKE) $(MACH).boot Scheme="$(SCHEME)" SCHEMEHEAPDIRS=: o=3 d=0 what=all
++
+ mach-make:
+ 	$(MAKE) config-scheme
+ 	cd $(SCHEME_WORKAREA) && $(MAKE)
+@@ -182,24 +197,33 @@ config-scheme:
+ 
+ scheme-cross:
+ 	env MAKE_BOOT_FOR_CROSS=yes SCHEME_SRC="$(SCHEME_DIR)" SCHEME_WORKAREA=$(SCHEME_WORKAREA) MACH="$(TARGET_MACH)" $(BOOTSTRAP_RACKET) "$(SCHEME_DIR)"/rktboot/make-boot.rkt
++	$(MAKE) finish-scheme-cross
++
++finish-scheme-cross:
+ 	$(SHELL) $(srcdir)/reset_boot.sh $(TARGET_MACH) $(SCHEME_WORKAREA)
+ 	cd $(SCHEME_WORKAREA) && "$(UP_SCHEME_DIR)"/configure @SCHEME_CROSS_CONFIG_ARGS@ $(SCHEME_CONFIG_VARS)
+ 	cd $(SCHEME_WORKAREA)/$(TARGET_MACH)/c && $(CHOST_HACK@T_CROSS_MODE@) $(MAKE) o=o cross=t
+-	$(MAKE) $(SCHEME_WORKAREA)/$(TARGET_MACH)/s/xpatch
++	$(MAKE) $(XPATCH_FILE)
++
++scheme-cross-via-scheme:
++	$(MAKE) $(SCHEME_WORKAREA)/boot/$(TARGET_MACH)/scheme.boot MACH=$(TARGET_MACH)
++	$(MAKE) finish-scheme-cross
+ 
+ # Rebuild patch file and cross "petite.boot" and "scheme.boot" when older
+-# than the build-host "scheme.boot" or when "make-boot.rkt" touchs dummy boot files
+-XPATCH_DEPS = $(SCHEME_HOST_WORKAREA)/$(MACH)/boot/$(MACH)/scheme.boot \
+-              $(SCHEME_WORKAREA)/boot/$(TARGET_MACH)/scheme.boot
++# than the build-<host "scheme.boot" or when "make-boot.rkt" touchs dummy boot files
++XPATCH_DEPS_built = $(SCHEME_HOST_WORKAREA)/$(MACH)/boot/$(MACH)/scheme.boot \
++                    $(SCHEME_WORKAREA)/boot/$(TARGET_MACH)/scheme.boot
++XPATCH_DEPS_existing = 
++XPATCH_DEPS = $(XPATCH_DEPS@USE_SCHEME_MODE@)
+ 
+-$(SCHEME_WORKAREA)/$(TARGET_MACH)/s/xpatch: $(XPATCH_DEPS)
++$(XPATCH_FILE): $(XPATCH_DEPS)
+ 	$(MAKE) bounce TARGET=build-xpatch-using-host
+ 
+ build-xpatch-using-host:
+ 	cd $(SCHEME_WORKAREA)/$(TARGET_MACH)/s && $(MAKE) -f Mf-cross m=$(MACH) xm=$(TARGET_MACH) Scheme="$(SCHEME_BIN)" SCHEMEHEAPDIRS="$(SCHEME_INC)"
+ 
+ XPATCH =
+-XPATCHcross = --xpatch $(SCHEME_WORKAREA)/$(TARGET_MACH)/s/xpatch
++XPATCHcross = --xpatch $(XPATCH_FILE)
+ 
+ racket.boot: racket.so
+ 	$(SCHEME) --script $(srcdir)/convert-to-boot.ss @BOOT_COMPRESS_COMP@ $(XPATCH@CROSS_MODE@) racket.so racket.boot $(TARGET_MACH)
+@@ -410,7 +434,7 @@ install-cross:
+ 	$(MAKE) compile-xpatch.$(TARGET_MACH)
+ 	$(MAKE) library-xpatch.$(TARGET_MACH)
+ 
+-SCHEME_XPATCH = $(SCHEME_WORKAREA)/$(TARGET_MACH)/s/xpatch
++SCHEME_XPATCH = $(XPATCH_FILE)
+ 
+ CROSS_SERVE_DEPS = $(srcdir)/mk-cross-serve.ss $(srcdir)/cross-serve.ss \
+                    $(srcdir)/../expander/env.ss $(srcdir)/../linklet/config.ss
+diff --git a/racket/src/cs/c/configure b/racket/src/cs/c/configure
+index 21695a431a..1eeef57753 100755
+--- a/racket/src/cs/c/configure
++++ b/racket/src/cs/c/configure
+@@ -654,6 +654,9 @@ MINGW
+ NOT_OSX
+ OSX
+ SETUP_BOOT_MODE
++USE_SCHEME_MODE
++MAKE_SCHEME_SCHEME
++MAKE_SCHEME_MODE
+ TT_CROSS_MODE
+ T_CROSS_MODE
+ CROSS_MODE
+@@ -1448,7 +1451,7 @@ Optional Features:
+   --enable-docs           build docs on install (enabled by default)
+   --enable-usersetup      setup user-specific files on install
+   --enable-racket=<path>  use <path> as Racket for build; or "auto" to create
+-  --enable-scheme=<path>  use <path> as host's build directory for cross
++  --enable-scheme=<path>  use <path> as host build for cross
+   --enable-mach=<mach>    use Chez Scheme machine type <mach>
+   --enable-target=<mach>  cross-build for Chez Scheme machine type <mach>
+   --enable-portable       prefer portable to host-specific
+@@ -2867,7 +2870,7 @@ show_explicitly_enabled "${enable_xonx}" "Unix style"
+ show_explicitly_enabled "${enable_libzo}" 'Compiled ".zo" files moved to lib'
+ 
+ show_explicitly_set "${enable_racket}" "Racket"
+-show_explicitly_set "${enable_scheme}" "Chez Scheme build directory"
++show_explicitly_set "${enable_scheme}" "Chez Scheme for build"
+ show_explicitly_set "${enable_mach}" "machine type"
+ show_explicitly_set "${enable_target}" "cross-build machine type"
+ show_explicitly_enabled "${enable_portable}" "portable"
+@@ -4745,9 +4748,21 @@ esac
+ 
+ SCHEME_DIR=${srcdir}/../../ChezScheme
+ MAKE_BUILD_SCHEME=checkout
++USE_SCHEME_MODE="_built"
++MAKE_SCHEME_MODE="${T_CROSS_MODE}"
+ 
+ if test "${enable_scheme}" != "" ; then
+-  CS_HOST_WORKAREA_PREFIX="${enable_scheme}/"
++   if test -d "${enable_scheme}" ; then
++     # Directory exists, so use it as a build directory
++     echo "Using supplied Scheme path as a build directory"
++     CS_HOST_WORKAREA_PREFIX="${enable_scheme}/"
++   else
++     # Directory does not exist, so assume it's an executable
++     echo "Using supplied Scheme path as an executable"
++     MAKE_SCHEME_MODE="${T_CROSS_MODE}-via-scheme"
++     MAKE_SCHEME_SCHEME="${enable_scheme}"
++     USE_SCHEME_MODE="_existing"
++   fi
+ fi
+ 
+ if test "${enable_racket}" != "" ; then
+@@ -6012,6 +6027,9 @@ SCHEME_CROSS_CONFIG_ARGS="--machine=${TARGET_MACH} --disable-x11 ${cs_auto_flags
+ 
+ 
+ 
++
++
++
+ 
+ 
+ 
+diff --git a/racket/src/cs/c/configure.ac b/racket/src/cs/c/configure.ac
+index 464ebe1760..aaee88156d 100644
+--- a/racket/src/cs/c/configure.ac
++++ b/racket/src/cs/c/configure.ac
+@@ -23,7 +23,7 @@ AC_ARG_ENABLE(compressmore, [  --enable-compressmore   compress compiled code ev
+ AC_ARG_ENABLE(compressboot, [  --enable-compressboot   compress boot files])
+ m4_include(../ac/path_arg.m4)
+ AC_ARG_ENABLE(racket,     [  --enable-racket=<path>  use <path> as Racket for build; or "auto" to create])
+-AC_ARG_ENABLE(scheme,     [  --enable-scheme=<path>  use <path> as host's build directory for cross])
++AC_ARG_ENABLE(scheme,     [  --enable-scheme=<path>  use <path> as host build for cross])
+ AC_ARG_ENABLE(mach,       [  --enable-mach=<mach>    use Chez Scheme machine type <mach>])
+ AC_ARG_ENABLE(target,     [  --enable-target=<mach>  cross-build for Chez Scheme machine type <mach>])
+ m4_include(../ac/portable_arg.m4)
+@@ -81,7 +81,7 @@ show_explicitly_disabled "${enable_compressboot}" "Compressed boot files"
+ show_explicitly_enabled "${enable_xonx}" "Unix style"
+ m4_include(../ac/path_show.m4)
+ show_explicitly_set "${enable_racket}" "Racket"
+-show_explicitly_set "${enable_scheme}" "Chez Scheme build directory"
++show_explicitly_set "${enable_scheme}" "Chez Scheme for build"
+ show_explicitly_set "${enable_mach}" "machine type"
+ show_explicitly_set "${enable_target}" "cross-build machine type"
+ m4_include(../ac/portable_show.m4)
+@@ -504,9 +504,21 @@ esac
+ 
+ SCHEME_DIR=${srcdir}/../../ChezScheme
+ MAKE_BUILD_SCHEME=checkout
++USE_SCHEME_MODE="_built"
++MAKE_SCHEME_MODE="${T_CROSS_MODE}"
+ 
+ if test "${enable_scheme}" != "" ; then
+-  CS_HOST_WORKAREA_PREFIX="${enable_scheme}/"
++   if test -d "${enable_scheme}" ; then
++     # Directory exists, so use it as a build directory
++     echo "Using supplied Scheme path as a build directory"
++     CS_HOST_WORKAREA_PREFIX="${enable_scheme}/"
++   else
++     # Directory does not exist, so assume it's an executable
++     echo "Using supplied Scheme path as an executable"
++     MAKE_SCHEME_MODE="${T_CROSS_MODE}-via-scheme"
++     MAKE_SCHEME_SCHEME="${enable_scheme}"
++     USE_SCHEME_MODE="_existing"
++   fi     
+ fi
+ 
+ if test "${enable_racket}" != "" ; then
+@@ -821,6 +833,9 @@ AC_SUBST(DIFF_MACH)
+ AC_SUBST(CROSS_MODE)
+ AC_SUBST(T_CROSS_MODE)
+ AC_SUBST(TT_CROSS_MODE)
++AC_SUBST(MAKE_SCHEME_MODE)
++AC_SUBST(MAKE_SCHEME_SCHEME)
++AC_SUBST(USE_SCHEME_MODE)
+ AC_SUBST(SETUP_BOOT_MODE)
+ AC_SUBST(OSX)
+ AC_SUBST(NOT_OSX)
+-- 
+2.32.0
+