ls and xfs = unhandled exception / reset

ls and xfs = unhandled exception / reset

[Alex Roman]

Hello,

I've got a linux system with the / partition as xfs (and no /boot
partition, blame kUbuntu's installer for that :)). I wanted to try to
boot the system from a grub2 floppy I made (so I can still boot my
system, no worries).

I do:
insmod ls
insmod pc
insmod xfs

Then if I do:
ls (hd0,1) -- my xfs partition

... the system just resets.

I verified that if I insmod ext2 and ls on an ext3 partition, it will
work as expected and not reset my PC. Also, if I ls on the xfs
partition, without the xfs module loaded, GRUB will just print
Filesystem type unknown, but won't reset.

Given that I'll also be working on adding CD-ROM boot support to GRUB
as part of GSoC, I figure this would be a great opportunity to start
fixing some bugs to get familiar with the code.

Now, I've no idea how to debug this issue, how to get a debugging log,
etc... Could anyone please point me at the right document to read or
give me some advice how I could start working on this?


Thank you in advance,
... regards!

-- 
Alex Roman <alex.roman@gmail.com>

Re: ls and xfs = unhandled exception / reset

[Robert Millan]

On Tue, May 15, 2007 at 08:47:03PM -0400, Alex Roman wrote:
> Hello,
> 
> I've got a linux system with the / partition as xfs (and no /boot
> partition, blame kUbuntu's installer for that :)). I wanted to try to
> boot the system from a grub2 floppy I made (so I can still boot my
> system, no worries).
> 
> I do:
> insmod ls
> insmod pc
> insmod xfs
> 
> Then if I do:
> ls (hd0,1) -- my xfs partition
> 
> ... the system just resets.
> 
> I verified that if I insmod ext2 and ls on an ext3 partition, it will
> work as expected and not reset my PC. Also, if I ls on the xfs
> partition, without the xfs module loaded, GRUB will just print
> Filesystem type unknown, but won't reset.
> 
> Given that I'll also be working on adding CD-ROM boot support to GRUB
> as part of GSoC, I figure this would be a great opportunity to start
> fixing some bugs to get familiar with the code.
> 
> Now, I've no idea how to debug this issue, how to get a debugging log,
> etc... Could anyone please point me at the right document to read or
> give me some advice how I could start working on this?

See:  http://grub.enbug.org/HowToDebug

-- 
Robert Millan

My spam trap is honeypot@aybabtu.com.  Note: this address is only intended
for spam harvesters.  Writing to it will get you added to my black list.

Re: ls and xfs = unhandled exception / reset

[Marco Gerards]

"Alex Roman" <alex.roman@gmail.com> writes:

Hi Alex,

> I've got a linux system with the / partition as xfs (and no /boot
> partition, blame kUbuntu's installer for that :)). I wanted to try to
> boot the system from a grub2 floppy I made (so I can still boot my
> system, no worries).
>
> I do:
> insmod ls
> insmod pc
> insmod xfs

One problem is that XFS support is not finished yet...

> Then if I do:
> ls (hd0,1) -- my xfs partition
>
> ... the system just resets.

Urgh, that is not supposed to happen :-).

> I verified that if I insmod ext2 and ls on an ext3 partition, it will
> work as expected and not reset my PC. Also, if I ls on the xfs
> partition, without the xfs module loaded, GRUB will just print
> Filesystem type unknown, but won't reset.

right, this sounds like a bug in XFS.

> Given that I'll also be working on adding CD-ROM boot support to GRUB
> as part of GSoC, I figure this would be a great opportunity to start
> fixing some bugs to get familiar with the code.

Agreed :-)

> Now, I've no idea how to debug this issue, how to get a debugging log,
> etc... Could anyone please point me at the right document to read or
> give me some advice how I could start working on this?

what I would do is trying to reproduce this bug in grub-emu.  You can
start grub-emu and attach gdb (or start from gdb).  When (if...) the
crash occur here, you can request a backtrace.  This is a more
comfortable way of debugging compared to doing this in qemu or so.

--
Marco