out of range pointer with ext2 filesystem

out of range pointer with ext2 filesystem

[richard juckes]

Hi, this is the problem I'm having with Grub2-cvs and ext2 filesystems.
I get a successful boot from a kernel on floppy with a fat filesystem,
but no luck when the same floppy is formatted with ext2.

Wed Feb 16 08:19:42 HKT 2005
--> cvs update
--> make clean
--> gcc --version
gcc (GCC) 4.0.0 20050213 (experimental)
Copyright (C) 2005 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is
NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.

--> ./configure
--> make
--> ./grub-mkimage -v -d . -o core.img _chain boot cat cmp ext2 fat
fshelp halt help linux ls normal pc reboot terminal
--> su mkdosfs /dev/fd0
--> dd if=boot.img of=/devfd0 bs=512 count=1
--> dd if=core.img of=/devfd0 bs=512 seek=1

reboot

GNU GRUB version 1.90

grub> ls
(fd0) (hd0) (hd0,0) (hd0,4) ..... (hd0,11)
grub> ls -l
Disk: fd0
Disk: hd0
unaligned pointer 0xfaa4
	
	and hangs

crtl-alt-delete
change floppy to one formatted with mkdosfs

grub> linux (fd0)/bzImage root=/dev/hda6
	[Linux-bzImage, setup=0xc00, size=0x10a925]
grub> boot

success!

make another kernel floppy

--# mke2fs /dev/fd0
mke2fs 1.36 (05-Feb-2005)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
184 inodes, 1440 blocks
72 blocks (5.00%) reserved for the super user
First data block=1
1 block group
8192 blocks per group, 8192 fragments per group
184 inodes per group

Writing inode tables: done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 31 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

reboot

grub> linux (fd0)/bzImage root=/dev/hda6
out of range pointer 0x7fca0

I had the same problem with yesterday's cvs, and also repeated the steps
with gcc-3.4.3 with similar results.
I hope this is useful,
Richard.
-- 
  richard juckes
  richardjuckes@fastmail.cn

Re: out of range pointer with ext2 filesystem

[Marco Gerards]

"richard juckes" <richardjuckes@fastmail.cn> writes:

> Hi, this is the problem I'm having with Grub2-cvs and ext2 filesystems.
> I get a successful boot from a kernel on floppy with a fat filesystem,
> but no luck when the same floppy is formatted with ext2.

[...]

> --> make
> --> ./grub-mkimage -v -d . -o core.img _chain boot cat cmp ext2 fat
> fshelp halt help linux ls normal pc reboot terminal
> --> su mkdosfs /dev/fd0
> --> dd if=boot.img of=/devfd0 bs=512 count=1
> --> dd if=core.img of=/devfd0 bs=512 seek=1

First you create a filesystem and after that you overwrite it.  I
doubt that it will work.

> reboot
>
> GNU GRUB version 1.90
>
> grub> ls
> (fd0) (hd0) (hd0,0) (hd0,4) ..... (hd0,11)
> grub> ls -l
> Disk: fd0
> Disk: hd0
> unaligned pointer 0xfaa4

In this example you use mkdosfs, or did you mean mkfe2fs?

> make another kernel floppy
>
> --# mke2fs /dev/fd0
> mke2fs 1.36 (05-Feb-2005)
> Filesystem label=
> OS type: Linux
> Block size=1024 (log=0)
> Fragment size=1024 (log=0)
> 184 inodes, 1440 blocks
> 72 blocks (5.00%) reserved for the super user
> First data block=1
> 1 block group
> 8192 blocks per group, 8192 fragments per group
> 184 inodes per group
>
> Writing inode tables: done
> Writing superblocks and filesystem accounting information: done
>
> This filesystem will be automatically checked every 31 mounts or
> 180 days, whichever comes first.  Use tune2fs -c or -i to override.
>
> reboot

You don't put GRUB on it?

> grub> linux (fd0)/bzImage root=/dev/hda6
> out of range pointer 0x7fca0

This is weird and should not happen.  A broken filesystem should never
cause a crash.  I will have a look at next weekend.

Thanks,
Marco