address@hidden: Bug#102811: grub: cannot access newer ext2 filesystems]

[Wilfried Weissmann]

Hi!

I think there is somewhere still a bug in the grub code (v 0.90). I am
still facing problems when the unix-grub-shell tries to find some files.
The oddity is that when I put as a bootloader on a floppy then I can
access files without any trouble. I have observed that the under unix
the offset for the inodes are not very well aligned (don't know about
the bios code, did't debug that one;). I guess the bios accesses are at
least sector aligned, while you can lseek() around in linux and the next
read() bails out when you are not on a block boundary. (Theory!)

I will still investigate a bit to me sure about what is going on...


rayn:~# debugfs /dev/mda2
debugfs 1.22, 22-Jun-2001 for EXT2 FS 0.5b, 95/08/09
debugfs:  stat /boot
Inode: 2301127   Type: directory    Mode:  0755   Flags: 0x0  
Generation: 4115339864
User:     0   Group:     0   Size: 4096
File ACL: 0    Directory ACL: 0
Links: 3   Blockcount: 8
Fragment:  Address: 0    Number: 0    Size: 0
ctime: 0x3b5f1a70 -- Wed Jul 25 21:13:52 2001
atime: 0x3b5f4163 -- Thu Jul 26 00:00:03 2001
mtime: 0x3b5f1a70 -- Wed Jul 25 21:13:52 2001
BLOCKS:
(0):4620822             <---- look good to me
TOTAL: 1
[snip]

Grub v 0.90 with E2DEBUG enabled:
grub>
 find /boot/vmlinuz
inode 2
dirname=/boot/vmlinuz
ipg=16320, dpb=128
group_id=0 group_desc=0 desc=0
fsblock 1 buffer 1075676160
inode table fsblock=5
fsblock 5 buffer 1075680256
ipb=32, sizeof(inode)=128
inode=401d9400, raw_inode=401d9480
offset into inode table block=128
00 00 00 00 00 00 00 00 fe 12 e9 3a fe 12 e9 3a
fe 12 e9 3a 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[snip]
logical block 0
returning 515
returning 515
fs block=515
fsblock 515 buffer 1075684480
directory entry ino=2301127
entry=boot^R<D6>)
inode 2301127
dirname=/vmlinuz
ipg=16320, dpb=128
group_id=141 group_desc=1 desc=13
fsblock 2 buffer 1075676160
inode table fsblock=4620293
fsblock 4620293 buffer 1075680256               <---- odd block alignmet
 
Error 15: File not found