GRUB has trouble "recognizing" bzImages?

[Tony Falcone]

Hi,

I have experienced the following problem using GRUB to boot my RedHat
7.2 system:

$ ls -l /boot produces

-rw-r--r--    1 root     root         5824 Jun 24  2001 boot.b
-rw-r--r--    1 root     root          612 Jun 24  2001 chain.b
drwxr-xr-x    2 root     root         1024 Jan  3 11:45 grub
-rw-r--r--    1 root     root        58487 Jan  3 11:05 
initrd-2.4.9-13custom.img
-rw-rw-r--    1 root     root       327765 Nov 12  2001 initrd-2.4.9-13.img
lrwxrwxrwx    1 root     root           14 Nov 12  2001 kernel.h -> 
kernel.h-2.4.9
-rw-r--r--    1 root     root          405 Nov 12  2001 kernel.h-2.4.9
drwxr-xr-x    2 root     root        12288 Oct 28  2001 lost+found
-rw-r--r--    1 root     root        23108 Jun 24  2001 message
lrwxrwxrwx    1 root     root           20 Nov 12  2001 module-info -> 
module-info-2.4.9-13
-rw-r--r--    1 root     root        13598 Oct 30  2001 module-info-2.4.9-13
-rw-r--r--    1 root     root          640 Jun 24  2001 os2_d.b
lrwxrwxrwx    1 root     root           19 Jan  3 10:35 System.map -> 
System.map-2.4.9-13
-rw-r--r--    1 root     root       434619 Oct 30  2001 System.map-2.4.9-13
-rw-r--r--    1 root     root       526414 Jan  3 10:19 
System.map-2.4.9-13custom
lrwxrwxrwx    1 root     root           16 Jan  3 10:34 vmlinuz 
->vmlinuz-2.4.9-13
-rw-r--r--    1 root     root       966565 Oct 30  2001 vmlinuz-2.4.9-13
-rw-r--r--    1 root     root      1113038 Jan  3 10:19 vmlinuz-2.4.9-13custom

while /boot/grub.conf looks like

# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this
file
# NOTICE:  You have a /boot partition.  This means that
#          all kernel and initrd paths are relative to /boot/, eg.
#          root (hd0,0)
#          kernel /vmlinuz-version ro root=/dev/hda5
#          initrd /initrd-version.img
#boot=/dev/hda
default=0
timeout=30
splashimage=(hd0,0)/grub/splash.xpm.gz
password --md5 $1$BëlcyßäÂ$Bb//S5JoPFxWa6dIWFYAP1
title Red Hat Linux (2.4.9-13)
        root (hd0,0)
        kernel /vmlinuz-2.4.9-13 ro root=/dev/hda5 vga=788
        initrd /initrd-2.4.9-13.img

title Red Hat Linux Custom (2.4.9-13custom)
        root (hd0,0)
        kernel /vmlinuz-2.4.9-13custom ro root=/dev/hda5 vga=788

when I attempt to boot, I get to GRUB stage 2, and the usual menu
listing

        Red Hat Linux (2.4.9-13)
        Red Hat Linux Custom (2.4.9-13custom)

If I choose the latter (i.e., the "Custom" version), GRUB starts to boot
the kernel, and then immediately reboots, taking me to the BIOS screen,
and then back to the GRUB menu.  If I choose the first kernel (the
original, non-custom one) then everything boots fine.

This is annoying, yet not yet strange...

So, I get back to the GRUB boot menu, enter "p", then my password, and
then "c" to get the command line.

At the command line I enter

grub> kernel /vmlinuz-2.4.9-13custom ro root=/dev/hda5 vga=788

and I get the error "Invalid or unsupported executable format," which is
strange since I am sure this is a bzImage.  Now, I need to boot up
anyway, so I then enter

grub> kernel /vmlinuz-2.4.9-13 ro root=/dev/hda5 vga=788

and AGAIN I get "Invalid or unsupported executable format."  But I
*know* this kernel boots, so what is happening here?  For kicks, I try

grub> kernel /vmlinuz ro root=/dev/hda5 vga=788

and THIS works!  So, what is going on?  /vmlinuz is a symbolic link to
/vmlinuz-2.4.9-13 - why is GRUB behaving this way?

(In the interest of completeness, let me say that, after typing

grub> kernel /vmlinuz ro root=/dev/hda5 vga=788

and getting a positive acknowledgment from GRUB that the kernel was
loaded, I typed

grub> boot

which did not work, since I omitted the initrd (see /boot and
/boot/grub.conf above.)  However, when I powered off/on, got to the GRUB
menu and then chose the first entry everything booted fine.)

Finally, the problem is *not* a missing "custom" initrd, since the
custom kernel was built specifically not to require any initrd.

Can anybody explain what is happening?  Thanks in advance.

-Tony

-- 
Tony Falcone, Principal Engineer
Alphatech, Inc.
6 New England Executive Park, Burlington, MA 01803
Email: address@hidden
Phone: (781) 273-3388, FAX: (781) 273-9345