Bug#565225: Resume device should be detected when creating initramfs, or not at all
* Sebastian Leske [Mon Nov 29, 2010 at 01:38:21 +0100]: I got bitten by this bug as well, similarly to Michael Conner above: I installed uswsusp to be able to hibernate/resume. s2disk worked flawlessly, but on booting the system simply did not bother to resume, booting normally instead. My analysis: After digging through the initramfs scripts, I discovered that this is because on booting resume is only triggered if $resume is set. As far as I understand, the initramfs takes $resume from the kernel command line (if set), and from /etc/initramfs-tools/conf.d/resume otherwise. In my case /etc/initramfs-tools/conf.d/resume did not exist. It should have been created by the preinst of initramfs-tools; however the preinst ( /var/lib/dpkg/info/initramfs-tools.preinst ) uses vol_id: [...] This will always fail, because vol_id is no longer part of Debian (it was removed from udev for version 146-1, see /usr/share/doc/udev/changelog.Debian.gz ). This is no longer true for current versions of initramfs-tools, JFYI. In summary: * Resume from hibernation will only work if /etc/initramfs-tools/conf.d/resume sets RESUME * However, there is no (working) code to write /etc/initramfs-tools/conf.d/resume, and no documentation explaining that it needs to be set manually to make resume work Thus, resume will probably fail to work in most cases. I believe there are actually several bugs here: 1) The code in the preinst of initramfs-tools to detect the swap partition does not work, because it uses vol_id. Fixed nowadays. 2) Even if 1) were fixed, there may be cases where the swap partition is incorrectly detected at installation time, or later changes. So fixing preinst is not enough. I agree with bug submitter jidanni that the swap partition should be detected when building the initramfs, not during preinst. 3) Additionally, I don't quite understand why uswsusp refuses to resume if $resume is not set (in /usr/share/initramfs-tools/scripts/local-premount/uswsusp ). The script does not actually use the value of $resume, it just aborts if it is not set :-(. I guess this could be considered a bug in uswsusp; I can report it against uswsusp if discussion of this bug indicates that this makes sense. To fix this, I would propose the following: * Drop the code in initramfs-tools.preinst which tries to write RESUME to /etc/initramfs-tools/conf.d/resume , which does not work anyway. Sounds reasonable too me. maximilian, what do you think of it? * Document (e.g. in /usr/share/doc/initramfs-tools/README.Debian ) that /etc/initramfs-tools/conf.d/resume can be used to set the resume device. * When building the initramfs, use the value from /etc/initramfs-tools/conf.d/resume if it exists; otherwise try to find it yourself: - if /etc/uswsusp.conf exists, it probably makes sense to read it (resume device =) - otherwise grab the current swap device (the config script from uswsusp already has code for that) This is still problematic if there is 1 swap device. Even better probably would be to use debconf to prompt for the resume device, if this is practical... I am willing to help implement / test this, but first I'll wait for some feedback if I'm even on the right track :-). Sorry that no one seemed to care about it for so long. What could be a proper way to resolve that nowadays, taking uswsusp, hibernate,... into account? dracut has some code in modules.d/95resume/. IMHO we should find a way which avoids duplicated code. Related bug reports: http://bugs.debian.org/574653 https://bugs.launchpad.net/ubuntu/+source/initramfs-tools/+bug/50437 regards, -mika- signature.asc Description: Digital signature
Bug#565225: Resume device should be detected when creating initramfs, or not at all
Hi,
I got bitten by this bug as well, similarly to Michael Conner above:
I installed uswsusp to be able to hibernate/resume.
s2disk worked flawlessly, but on booting the system simply did not
bother to resume, booting normally instead.
My analysis:
After digging through the initramfs scripts, I discovered that this is
because on booting resume is only triggered if $resume is set.
As far as I understand, the initramfs takes $resume from the kernel
command line (if set), and from /etc/initramfs-tools/conf.d/resume
otherwise.
In my case /etc/initramfs-tools/conf.d/resume did not exist.
It should have been created by the preinst of initramfs-tools; however
the preinst ( /var/lib/dpkg/info/initramfs-tools.preinst ) uses vol_id:
---snip
# First time install. Can we autodetect the RESUME partition?
if [ -r /proc/swaps ]; then
RESUME=$(tail -n $(($(wc -l /proc/swaps | awk ' { print
$1 } ') - 1)) /proc/swaps | sort -rk3 | head -n 1 | awk ' { print $1 } ')
if command -v vol_id /dev/null 21; then
UUID=$(vol_id -u $RESUME || true)
elif [ -x /lib/udev/vol_id ]; then
UUID=$(/lib/udev/vol_id -u $RESUME || true)
fi
if [ -n $UUID ]; then
RESUME=UUID=$UUID
fi
fi
---snap---
This will always fail, because vol_id is no longer part of Debian (it was
removed from udev for version 146-1, see
/usr/share/doc/udev/changelog.Debian.gz ).
In summary:
* Resume from hibernation will only work if /etc/initramfs-tools/conf.d/resume
sets RESUME
* However, there is no (working) code to write
/etc/initramfs-tools/conf.d/resume, and no documentation explaining that it
needs to be set manually to make resume work
Thus, resume will probably fail to work in most cases.
I believe there are actually several bugs here:
1) The code in the preinst of initramfs-tools to detect the swap partition does
not work, because it uses vol_id.
2) Even if 1) were fixed, there may be cases where the swap partition is
incorrectly detected at installation time, or later changes. So fixing
preinst is not enough.
I agree with bug submitter jidanni that the swap partition should be detected
when building the initramfs, not during preinst.
3) Additionally, I don't quite understand why uswsusp refuses to resume if
$resume is not set (in
/usr/share/initramfs-tools/scripts/local-premount/uswsusp ).
The script does not actually use the value of $resume, it just aborts if it
is not set :-(.
I guess this could be considered a bug in uswsusp; I can report it against
uswsusp if discussion of this bug indicates that this makes sense.
To fix this, I would propose the following:
* Drop the code in initramfs-tools.preinst which tries to write RESUME to
/etc/initramfs-tools/conf.d/resume , which does not work anyway.
* Document (e.g. in /usr/share/doc/initramfs-tools/README.Debian ) that
/etc/initramfs-tools/conf.d/resume can be used to set the resume device.
* When building the initramfs, use the value from
/etc/initramfs-tools/conf.d/resume
if it exists; otherwise try to find it yourself:
- if /etc/uswsusp.conf exists, it probably makes sense to read it (resume
device =)
- otherwise grab the current swap device (the config script from uswsusp
already has code for that)
This is still problematic if there is 1 swap device. Even better probably
would be to use debconf to prompt for the resume device, if this is
practical...
I am willing to help implement / test this, but first I'll wait for some
feedback if I'm even on the right track :-).
Greetings,
S.Leske
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