Guix hurd with rumpdisk boots! [WAS Re: Some progress, Guix rumpdisk still crashes...]

[Janneke Nieuwenhuizen]

Sergey Bugaev writes:

Hello Sergey,

> On Wed, May 17, 2023 at 9:25 PM Janneke Nieuwenhuizen <janneke@gnu.org> wrote:

> I've recently been doing this kind of debugging early boot-up process
> *a lot*, so maybe I could provide some tips indeed. For getting more
> lines of output, try console=com0 on gnumach cmdline, and run qemu
> with -nographic -serial stdio or something like that.

Now that was really a great help, thanks!  It helped me (e)diff many
different qemu runs: plain debian, debian+guix/pci-arbiter,
debian+guix/pci-arbiter+guix/rumpdisk, plain guix,
guix+debian/pci-arbiter, guix+debian/pci-arbiter+debian/rumpdisk...

It was immediately obvious that the messages from rumpdisk were (nearly)
identical.  As the boot went silent at the end I assumed a crash or a
hang in rumpdisk.  After inspecting the diffs and seeing nothing really
different, I noticed that I used -m 4096 for debian and -m 1024 for guix
on the qemu command line.  Do'h, turns out rumpdisk needs at least
1200MB...

With

    https://gitlab.com/janneke/guix/-/tree/wip-hurd

I've now succesfully been doing

--8<---------------cut here---------------start------------->8---
./pre-inst-env guix system image -t hurd-raw gnu/system/examples/bare-hurd.tmpl
cp /gnu/store/r5dpblnfsj08jh3hdmn8s6l9xaczwn65-disk-image guix.img
sudo losetup -o $((512*2048)) /dev/loop0 guix.img
sudo mount /dev/loop0 /mnt
edit /mnt/boot/grub/grub.cfg, adding console=com0
sudo umount /mnt
--8<---------------cut here---------------end--------------->8---

and then

--8<---------------cut here---------------start------------->8---
guix shell qemu -- qemu-system-i386                     \
-m 4096                                                 \
--enable-kvm                                            \
--device rtl8139,netdev=net0                            \
--netdev user,id=net0,hostfwd=tcp:0.0.0.0:11022-:2222   \
--snapshot                                              \
--no-reboot                                             \
--device virtio-serial-pci                              \
--nographic                                             \
--serial mon:stdio                                      \
--hda r5dpblnfsj08jh3hdmn8s6l9xaczwn65-disk-image+CONSOLE=COM0
--8<---------------cut here---------------end--------------->8---

Just for fun, find the succesful log attached.

Is there a way to pass the "console=com0" argument from the QEMU command
line?  That would be nice!

> Other than that, just attach gdb and see what it crashes on? Like this:
>
> $ gdb /path/to/gnumach
> (gdb) tar rem :1234
> (gdb) b i386_exception
> (gdb) b task_terminate
> (gdb) b Panic
> (gdb) add-symbol-file /path/to/rumpdisk.static
> blah-blah (y/n?) y
> (gdb) c

[..]

Ah, I had no idea; this is so helpful.  Maybe a good idea to have this
on the website/wiki, right?

Greetings,
Janneke

guix-glibc.log
Description: Binary data

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Janneke Nieuwenhuizen <janneke@gnu.org>  | GNU LilyPond https://LilyPond.org
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