On 8/3/2010 11:47 AM, Edward Diener wrote:
> On 8/3/2010 11:13 AM, Les Mikesell wrote:
>> On 8/3/2010 9:56 AM, Edward Diener wrote:
>>>
>>> I am at the shell prompt but in order to get grub to work, don't I need
>>> to mount my actual boot and root partitions for grub to know that
>>> (hd0,9) refers a valid boot partition when I tell grub:
>>>
>>> root (hd0,9)
>>> setup (hd0,9)
>>
>> No, grub doesn't need to have anything mounted.
>
> OK, thanks for the info.
>
>> The sysimage mount and
>> chroot is most useful to get access to your usual tools in their usual
>> paths and to be able to edit the grub.conf file. I've never tried to
>> boot from a partition that far into the disk, though. I had enough
>> trouble back in the days when bios only knew 1024 cylinders that I've
>> always put a small /boot partition as the first thing on the disk even
>> though you shouldn't have to now.
>
> My problem was that once I did a chroot I did not have any /dev devices.
> Evidently grub does use this. Once I did:
>
> mount --bind /dev /mnt/sysimage/dev
>
> before doing:
>
> chroot /mnt/sysimage
>
> when I executed 'grub' it found the (hd0,9) partition.
>
> From what you say above I did not even have to mount my system off of
> /mnt/sysimage and changed my root there, but just could have executed
> 'grub' from the command prompt and re-initialized my boot partition.
I've never quite understood how grub maps its drive description syntax
into what linux uses (hopefully matching what bios will see at boot...)
but it probably does need to find the names in /dev. But it shouldn't
matter if the partition is mounted or not if you don't need to edit the
config file or rebuild the initrd.
--
Les Mikesell
lesmikesell at gmail.com