| Message ID | 87zhawax60.fsf@m4x.org |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [bug#40927] Allow resume from swap device during boot | expand |
| Context | Check | Description |
|---|---|---|
| cbaines/comparison | success | View comparision |
| cbaines/git branch | success | View Git branch |
| cbaines/applying patch | fail | View Laminar job |
Hi Jean-Baptiste Note,
On Tue, 28 Apr 2020 07:26:15 +0000
Jean-Baptiste Note <jean-baptiste.note@m4x.org> wrote:
> linux-libre/Documentation/swsusp.txt
Should be linux-libre/Documentation/power/swsusp.txt .
Otherwise OK.
Please try to find the names of the actual authors so we can commit the parts
they wrote with them as author.
Who provides the "resume=" argument eventually?
Also, if we want to support this, what would the Guix installer have to do?
Add a swap partition? Does it have to be exactly as big as the amount of RAM
or does it need to be bigger because of overhead?
Jean-Baptiste, Jean-Baptiste Note 写道： > This is a very important feature for people like me using GUIX > SD on a > laptop (yes, it is possible, mine is a corebooted X230 running > linux-libre!) Greetings, brother in hardware. Note that hibernation and resumption already work fine if you rely on the kernel's built-in support. I've been hibernating my X230T for years without patches. This explicit initramfs support is only needed if your storage drivers aren't available when the kernel itself tries to resume, and the initramfs has to retry later. That's slower but allows things like ahci to be modular instead of built-in. > This patch is based on a patch floating around. The core > functionality > has been isolated, the resume function isolated, the patch > rebased and > tested. I'm not taking credit for it, even though tracing the > exact > origin is hard. Heh. It's certainly very similar to a patch of mine that's ‘out there’ although it's probably not the only one. > The resume hook is called if the resume= kernel argument is > provided, > which one can do during system configuration. This patch ignores the ‘noresume’ flag, which is bad. If it's present anywhere on the command line resumption should be skipped: + (when (and (not (member "noresume" args)) + resume-device + (file-exists? resume-device) + (file-exists? "/sys/power/resume")) + (resume-from-device resume-device)) > My scheme level is zero, so please bear with me. In particular, > some > conditionals could maybe be moved within the function, I'd like to see everything moved into a self-contained DTRT [try-to-]resume procedure, except for the ‘noresume’ check (so callers are free to explicitly resume if they so please): + (unless (member "noresume" args) + (resume-if-hibernated (find-long-option "resume" args))) This is what the last iteration of my patch does. If (find-long-option "resume" args) is #f, fall back to CONFIG_PM_STD_PARTITION. This is what the kernel does: even if ‘resume=’ is missing, it will try to resume from that device if specified. We should match that behaviour if we can. Problem is, I forgot how to get that value from user space, or if it's even possible. I gave up on Linux's built-in hibernation (swsusp) years ago. It's poorly written and maintained, and the author fiercely defends it from all improvement. Instead I use TuxOnIce, which exposes it under /sys/power/tuxonice/…. That's obviously not an option here, although it would be friendly to fall back to it for us ToI users :-) *user. I think ToI even exposes the ‘last used hibernation device’ somewhere, so user space can just use that instead of CONFIG_PM_STD_PARTITION. This is obviously the right thing to do. Again, not sure if swsusp does. > or the function itself called within some already-available > hooks. We don't have a concept of ‘initramfs hooks’ and I think that's a good thing. Gives me dracut flashbacks. Don't lets bother with them until we need them, which is never. > Also it is not clear if the commit log is adequate for such a > change. It's all right :-) If anything, it's too long: linux-boot: Add support for resuming from swap device. * gnu/build/linux-boot.scm (resume-from-device): New procedure. * gnu/build/linux-boot.scm (boot-system): Call it, unless ‘noresume’ is present on the kernel command line. > Please let me know how to improve this and get this merged; I > can also > write some documentation (probably once the mechanism is in > place) to > explain how the feature can be used. If this works properly no documentation is needed. The kernel by default writes to the first swap device; we should magically resume from it. Forcing users to know (or care) about part 2 is asymmetrical and wrong. Not sure if that's possible with vanilla Linux-Libre… Will stop shilling ToI for now, T G-R
Hibernation has been supported on Guix Systems for a very long time now. I'm not aware of any, but any failures to hibernate are probably configuration or hardware-specific and should be reported as new bugs. Kind regards, T G-R
From 2531d1d08dabb53ff15020aedcec2ad5d8e6c600 Mon Sep 17 00:00:00 2001 From: Jean-Baptiste Note <jean-baptiste.note@m4x.org> Date: Mon, 27 Apr 2020 20:42:03 +0000 Subject: [PATCH] linux-boot: Add support for resuming from swap device. * gnu/build/linux-boot.scm (resume-from-device): Add function. * gnu/build/linux-boot.scm (boot-system): Add hook calling resume-from-device if specified on commandline, before mounting any actual disk filesystems. --- gnu/build/linux-boot.scm | 43 +++++++++++++++++++++++++++++++++++++--- 1 file changed, 40 insertions(+), 3 deletions(-) diff --git a/gnu/build/linux-boot.scm b/gnu/build/linux-boot.scm index 4fb711b8f2..907c84276f 100644 --- a/gnu/build/linux-boot.scm +++ b/gnu/build/linux-boot.scm @@ -357,6 +357,37 @@ the last argument of `mknod'." (compose (cut string=? program <>) basename)))) (filter-map string->number (scandir "/proc"))))) +(define (resume-from-device resume-device) + "Resume from hibernation state on device DEVICE. This *must* happen before +we mount any filesystems on disk. See +linux-libre/Documentation/swsusp.txt. Please note that this function will not +return if resume happens successfully, and will return if swap device does not +contain a valid resume signature." + (false-if-exception + (let* ((device-base-name + ;; The base name of the device file, after resolving + ;; symlinks. + (let loop ((file resume-device)) + (match (stat:type (lstat file)) + ('symlink + (let ((target (readlink file))) + (if (string-prefix? "/" target) + (loop target) + (loop (string-append (dirname file) "/" target))))) + (_ (basename file))))) + (major+minor + ;; The major:minor string (e.g. "8:2") corresponding + ;; to the resume device. + (call-with-input-file (string-append "/sys/class/block/" + device-base-name + "/dev") + read-line))) + ;; Write the major:minor string to /sys/power/resume + ;; to attempt resume from hibernation. + (when major+minor + (call-with-output-file "/sys/power/resume" + (cut display major+minor <>)))))) + (define* (mount-root-file-system root type #:key volatile-root? (flags 0) options) "Mount the root file system of type TYPE at device ROOT. If VOLATILE-ROOT? is @@ -493,9 +524,10 @@ upon error." (call-with-error-handling (lambda () (mount-essential-file-systems) - (let* ((args (linux-command-line)) - (to-load (find-long-option "--load" args)) - (root (find-long-option "--root" args))) + (let* ((args (linux-command-line)) + (to-load (find-long-option "--load" args)) + (root (find-long-option "--root" args)) + (resume-device (find-long-option "resume" args))) (when (member "--repl" args) (start-repl)) @@ -528,6 +560,11 @@ upon error." (unless (pre-mount) (error "pre-mount actions failed"))) + (when (and resume-device + (file-exists? resume-device) + (file-exists? "/sys/power/resume")) + (resume-from-device resume-device)) + (setenv "EXT2FS_NO_MTAB_OK" "1") (if root -- 2.26.1