From: ludo@gnu.org (Ludovic Courtès)
To: Mark H Weaver <mhw@netris.org>
Cc: guix-devel@gnu.org
Subject: Re: [PATCH] PRELIMINARY: Add support for hibernation.
Date: Fri, 02 Sep 2016 15:03:16 +0200 [thread overview]
Message-ID: <8737lilai3.fsf@gnu.org> (raw)
In-Reply-To: <87bn0u1msx.fsf@netris.org> (Mark H. Weaver's message of "Mon, 15 Aug 2016 04:03:26 -0400")
Hello!
Mark H Weaver <mhw@netris.org> skribis:
> Here's a preliminary patch to add support for hibernation. To enable
> it, you'll also need to add a line like this to your 'operating-system'
> definition.
>
> (kernel-arguments '("resume=/dev/sda2"))
>
> Where the device named is a swap partition.
Awesome! I missed this.
> It may be that we should add a dedicated 'resume-device' field to the
> 'operating-system'. Thoughts?
I think it’s OK this way (though we should give an example in the
manual), but not strong opinion.
> From ad1d583eb6f009a2dfbc284cb8368608caf27a05 Mon Sep 17 00:00:00 2001
> From: Mark H Weaver <mhw@netris.org>
> Date: Sun, 14 Aug 2016 05:33:12 -0400
> Subject: [PATCH] PRELIMINARY: Add support for hibernation.
>
> * gnu/build/linux-boot.scm (boot-system): Look for a resume=<device-name>
> argument on the linux command line, and if present, attempt to resume from
> hibernation.
> * gnu/services/desktop.scm (<elogind-configuration>): Change the default
> value of the 'handle-hibernate-key' key to 'hibernate'.
[...]
> + (resume-device (find-long-option "resume" args)))
Could you mention this argument under “Initial RAM Disk”?
> + ;;
> + ;; Attempt to resume from hibernation.
> + ;;
> + ;; IMPORTANT: This *must* happen before we mount any filesystems on
> + ;; disk. Quoting linux-libre/Documentation/swsusp.txt:
> + ;;
> + ;; * BIG FAT WARNING **************************************************
> + ;; *
> + ;; * If you touch anything on disk between suspend and resume...
> + ;; * ...kiss your data goodbye.
> + ;; *
> + ;; * If you do resume from initrd after your filesystems are mounted...
> + ;; * ...bye bye root partition.
> + ;; * [this is actually same case as above]
> + ;; *
> + (when (and resume-device
> + (file-exists? resume-device)
> + (file-exists? "/sys/power/resume"))
> + (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 <>))))))
Could you turn the (false-if-exception …) expression into a separate
procedure?
I would perhaps remove ‘false-if-exception’: that way, if something goes
wrong, we’ll be able to see what the error is and get a REPL. It might
also be useful to display a message like “resuming from device /dev/xyz
(8:2)…”
Apart from that it seems alright!
It’d be interesting to see if we can write a test. The existing tests
do not use a swap partition, but adding one shouldn’t be too hard.
Thank you,
Ludo’.
prev parent reply other threads:[~2016-09-02 13:03 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-15 8:03 [PATCH] PRELIMINARY: Add support for hibernation Mark H Weaver
2016-08-15 19:57 ` Tomáš Čech
2016-09-02 13:03 ` Ludovic Courtès [this message]
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