From: ludo@gnu.org (Ludovic Courtès)
To: Chris Marusich <cmmarusich@gmail.com>
Cc: guix-devel@gnu.org
Subject: Re: GuixSD on servers [Fwd: [rtracker.1984.is #131647] A question about VServer system specific requirements]
Date: Wed, 19 Apr 2017 22:59:15 +0200 [thread overview]
Message-ID: <8760i0m7vg.fsf@gnu.org> (raw)
In-Reply-To: <87k26hwxt0.fsf@gmail.com> (Chris Marusich's message of "Tue, 18 Apr 2017 08:16:43 -0700")
Heya,
Chris Marusich <cmmarusich@gmail.com> skribis:
> I've been looking into this off and on over the last few weeks, but I
> haven't made any breakthroughs. The closest I got was this:
>
> 1) Create a disk image for testing:
>
> ./pre-inst-env guix system --root=/tmp/disk-image-gc-root --fallback disk-image ~/guix/gnu/system/install.scm
> cp $the_resulting_path /tmp/disk-image
>
> 2) Try to boot it (with an attached hard disk), and watch it fail:
>
> qemu-img create -f qcow2 /tmp/test 10G
> sudo qemu-system-x86_64 -machine type=pc-i440fx-2.5,accel=kvm -boot order=dc,menu=on -m size=4G -k en-us -name guixsd -cdrom "/tmp/disk-image" "/tmp/test"
>
> 3) Mount it as loopback device:
>
> sudo losetup -P /dev/loop0 /tmp/disk-image
> sudo mkdir /mnt/disk-image-partition-1
> sudo mount /dev/loop0p1 /mnt/disk-image-partition-1
>
> 4) Make a bootable CD-ROM image of it (see (grub) Invoking grub-mkrescue):
>
> sudo grub-mkrescue -o /tmp/test-img.iso /mnt/disk-image-partition-1
>
> 5) Try to boot (partial success):
>
> sudo qemu-system-x86_64 -machine type=pc-i440fx-2.5,accel=kvm -boot order=dc,menu=on -m size=4G -k en-us -name guixsd -cdrom "/tmp/disk-image" "/tmp/test"
>
> There appear to be (at least) two problem that prevent this naive
> solution from working, which might point us in the right direction:
>
> First, the GRUB menu is trying to find a file system with label
> "gnu-disk-image" (via "search --label --set gnu-disk-image"), which
> won't work because there is no file system with that label in the
> resulting image.
So it seems that the crux of the problem is that ISO9660 lacks file
system labels, which breaks the whole thing, right?
> Possible fix: the manual for grub-mkrescue says "The
> root device will be set up appropriately on entering your 'grub.cfg'
> configuration file", so perhaps we can simply omit our --search. FYI,
> the boot process continues successfully past this point precisely
> because GRUB has already set the root; the fact that our search command
> failed generates an error message but does not change the fact that it
> succeeds in booting to the initrd.
Good.
> Second, the init process from the initrd (I think that's what it's
> called?) is trying to look for a file system with label
> "gnu-disk-image", which it never finds. It just sits there waiting to
> find it, and it never shows up, so it freaks out. Possible solution:
> modify the behavior of our initrd's init process. I'm not sure how to
> customize the init process here, but there must be a way. We'll
> probably also need the kernel module that enables reading of iso9660
> file systems, if it wasn't present already.
So we could try detecting the root partition by a mechanism other than
partition labels/UUIDs, but I don’t know which mechanism. Ideas? How
do people address this?
> If you don't like grub-mkrescue, you can "roll your own" ISO generation
> program, like Nix does by customizing the xorriso invocation [1]... But
> honestly, it looks pretty complicated [2]. So if we can let
> grub-mkrescue do that work for us, that would be swell.
Indeed, though of course grub-mkrescue invokes xorriso behind the
scenes.
Once we’ve figured out the partition designation issue above, I guess we
could integrate that and have, say,
guix system iso-image …
to produce an ISO image. Sounds doable!
Thanks for the explanations,
Ludo’.
next prev parent reply other threads:[~2017-04-19 20:59 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-18 14:17 GuixSD on servers [Fwd: [rtracker.1984.is #131647] A question about VServer system specific requirements] ng0
2017-04-18 15:16 ` Chris Marusich
2017-04-19 20:59 ` Ludovic Courtès [this message]
2017-04-23 4:52 ` Chris Marusich
2017-04-24 5:11 ` GuixSD bootable ISO-9669 image (was: Re: GuixSD on servers [Fwd: [rtracker.1984.is #131647] A question about VServer system specific requirements]) Chris Marusich
2017-04-27 13:42 ` GuixSD bootable ISO-9669 image Ludovic Courtès
2017-04-27 17:08 ` GuixSD bootable ISO-9669 image (was: Re: GuixSD on servers [Fwd: [rtracker.1984.is #131647] A question about VServer system specific requirements]) Danny Milosavljevic
2017-04-27 20:00 ` Danny Milosavljevic
2017-04-28 8:18 ` Danny Milosavljevic
2017-05-02 12:37 ` GuixSD bootable ISO-9669 image Ludovic Courtès
2017-05-02 12:53 ` ng0
2017-05-03 6:26 ` Mark H Weaver
2017-05-02 20:09 ` Danny Milosavljevic
2017-05-02 21:11 ` Ludovic Courtès
2017-05-07 19:37 ` Danny Milosavljevic
2017-05-08 14:14 ` Ludovic Courtès
2017-05-11 23:30 ` Danny Milosavljevic
2017-05-12 15:33 ` Ludovic Courtès
2017-05-14 21:25 ` Danny Milosavljevic
2017-05-16 8:31 ` Ludovic Courtès
2017-06-06 9:35 ` Danny Milosavljevic
2017-06-08 12:25 ` Ludovic Courtès
2017-05-02 20:12 ` Danny Milosavljevic
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://guix.gnu.org/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=8760i0m7vg.fsf@gnu.org \
--to=ludo@gnu.org \
--cc=cmmarusich@gmail.com \
--cc=guix-devel@gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/guix.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).