Re: How to boot alternative Debian version safely?
On 11 Feb 2005, Gene Heskett wrote:
> >Thanks to all for replies. I've now managed to get Grub to access
> > the partition but I get the following kernel error:
> >
> > Cannot open root device "hda7" or unknown block (0,0)
> >
> >My Grub entry is as follows:
> >
> >
> >title Debian test system, kernel 2.6.8-1-386
> >root (hd0,6)
> >kernel /boot/vmlinuz-2.6.8-1-386 root=/dev/hda7 ro
> >savedefault
> >boot
> >
> >Anyone spot the error here?
> >
> >Anthony
> Did your email agent wrap the above?
>
> In any event, you are specifying a seperate boot partition with the
> line 'root (hd0,6)' above, so the next 'kernel' line s/b relative to
> that. In other words:
>
> kernel /vmlinuz-2.6.8-1-386 ro root=/dev/hda7
>
> because there is not a /boot directory within the /boot partition,
> then the path to vmlinuz becomes relative to the 'root (hd0,6)'
> aka /boot partition. I assume your '/' partition is /dev/hda7?
>
> And what is the
> savedefault
> boot
> ??
>
> The normal grub install has a few lines of comments above the actual
> entries, and I'm wondering where they went.
>
Responding to you and Clive, here is my whole menu.lst. I don't know
what savedefault and boot are doing but they were placed there by the
automatic grub installation by Debian so I presumed they were needed.
I just copied the existing entries and modified them to point at the new
partition.
The last entry on the list is for a kernel I compiled myself earlier and
that does boot.
# menu.lst - See: grub(8), info grub, update-grub(8)
# grub-install(8), grub-floppy(8),
# grub-md5-crypt, /usr/share/doc/grub
# and /usr/share/doc/grub-doc/.
## default num
# Set the default entry to the entry number NUM. Numbering starts from 0, and
# the entry number 0 is the default if the command is not used.
#
# You can specify 'saved' instead of a number. In this case, the default entry
# is the entry saved with the command 'savedefault'.
default 0
## timeout sec
# Set a timeout, in SEC seconds, before automatically booting the default entry
# (normally the first entry defined).
timeout 5
# Pretty colours
color cyan/blue white/blue
## password ['--md5'] passwd
# If used in the first section of a menu file, disable all interactive editing
# control (menu entry editor and command-line) and entries protected by the
# command 'lock'
# e.g. password topsecret
# password --md5 $1$gLhU0/$aW78kHK1QfV3P2b2znUoe/
# password topsecret
#
# examples
#
# title Windows 95/98/NT/2000
# root (hd0,0)
# makeactive
# chainloader +1
#
# title Linux
# root (hd0,1)
# kernel /vmlinuz root=/dev/hda2 ro
#
#
# Put static boot stanzas before and/or after AUTOMAGIC KERNEL LIST
### BEGIN AUTOMAGIC KERNELS LIST
## lines between the AUTOMAGIC KERNELS LIST markers will be modified
## by the debian update-grub script except for the default optons below
## DO NOT UNCOMMENT THEM, Just edit them to your needs
## ## Start Default Options ##
## default kernel options
## default kernel options for automagic boot options
## If you want special options for specifiv kernels use kopt_x_y_z
## where x.y.z is kernel version. Minor versions can be omitted.
## e.g. kopt=root=/dev/hda1 ro
# kopt=root=/dev/hdb10 ro
## default grub root device
## e.g. groot=(hd0,0)
# groot=(hd1,9)
## should update-grub create alternative automagic boot options
## e.g. alternative=true
## alternative=false
# alternative=true
## should update-grub lock alternative automagic boot options
## e.g. lockalternative=true
## lockalternative=false
# lockalternative=false
## altoption boot targets option
## multiple altoptions lines are allowed
## e.g. altoptions=(extra menu suffix) extra boot options
## altoptions=(recovery mode) single
# altoptions=(recovery mode) single
## controls how many kernels should be put into the menu.lst
## only counts the first occurence of a kernel, not the
## alternative kernel options
## e.g. howmany=all
## howmany=7
# howmany=all
## should update-grub create memtest86 boot option
## e.g. memtest86=true
## memtest86=false
# memtest86=true
## ## End Default Options ##
title Debian GNU/Linux, kernel 2.6.10-1-686
root (hd1,9)
kernel /boot/vmlinuz-2.6.10-1-686 root=/dev/hdb10 ro
initrd /boot/initrd.img-2.6.10-1-686
savedefault
boot
title Debian GNU/Linux, kernel 2.6.10-1-686 (recovery mode)
root (hd1,9)
kernel /boot/vmlinuz-2.6.10-1-686 root=/dev/hdb10 ro single
initrd /boot/initrd.img-2.6.10-1-686
savedefault
boot
title Debian test system, kernel 2.6.8-1-386
root (hd0,6)
kernel /boot/vmlinuz-2.6.8-1-386 root=/dev/hda7 ro
savedefault
boot
title Debian GNU/Linux, kernel bzimage.268
root (hd1,9)
kernel /boot/bzimage.268 root=/dev/hdb10 ro
savedefault
boot
### END DEBIAN AUTOMAGIC KERNELS LIST
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