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Re: Status of hibernation (suspend to disk) in Guix
From: |
Ivan Vilata i Balaguer |
Subject: |
Re: Status of hibernation (suspend to disk) in Guix |
Date: |
Wed, 14 Dec 2022 10:43:46 +0100 |
Ivan Vilata i Balaguer (2022-12-12 21:11:53 +0100) wrote:
> Mekeor Melire (2022-12-10 01:00:24 +0000) wrote:
>
> > > What about the "filefrag" executable from the "e2fsprogs" package.
> > > According to this article, it can be used in place of the deprecated
> > > uswsusp suite:
> > >
> > > https://www.linuxuprising.com/2021/08/how-to-enable-hibernation-on-ubuntu.html
>
> Good find! Besides the issue of `filefrag` being ExtFS-specific, another
> thing that worries me is [this check][1] that `swap-offset` does about the
> swap header being physically contiguous on disk, which would need to be made
> manually with `filefrag`.
>
> [1]:
> https://git.kernel.org/pub/scm/linux/kernel/git/rafael/suspend-utils.git/tree/swap-offset.c#n114
I had a quick look to the [source code of mkswap][1] and it does take care of
checking whether the swap file has holes in it (look for the word "hole"). If
it has, it prints a warning (but it continues). For instance:
```
$ dd if=/dev/zero of=swap bs=512 count=1 seek=1000
1+0 records in
1+0 records out
512 bytes copied, 0.000234313 s, 2.2 MB/s
$ mkswap swap
mkswap: swap contains holes or other unsupported extents.
This swap file can be rejected by kernel on swap activation!
Use --verbose for more details.
Setting up swapspace version 1, size = 496 KiB (507904 bytes)
no label, UUID=3c5920cb-04ee-4713-8008-c2c1bebc2f6f
```
[1]: https://github.com/util-linux/util-linux/blob/master/disk-utils/mkswap.c
Since it's unlikely that the file will change its block arrangement on disk,
and enlarging it requires another invocation of `mkswap`, it's probably enough
to tell the user to check for such warnings on `mkswap` invocation (in section
"(guix)Keyboard Layout, Networking, and Partitioning"), and then instructing
them to use `filefrag` in "(guix)Swap Space" should be ok.
I can work on an additional patch for that, but I can't ensure that it'll be
ready before 1.4.0 (I'm not in the dev team, so I don't know what the planning
for the release is 😉).
Cheers!
--
Ivan Vilata i Balaguer -- https://elvil.net/
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Re: Status of hibernation (suspend to disk) in Guix, Mekeor Melire, 2022/12/09