Re: Switching to another boot device on failure

[Venkata Subbarao]

I purposefully modified grub.cfg and changed the UUID in the line starts with "linux /boot/vmlinuz...... root=UUID=XXXX"

Ended up in the (initramfs) prompt because such partition is not present. Hence, I was thinking of checking CRC.

Thanks and Regards,

Subbarao

On Thu, Nov 20, 2014 at 10:53 PM, Andrei Borzenkov <address@hidden> wrote:

В Thu, 20 Nov 2014 19:08:10 +0530
Venkata Subbarao <address@hidden> пишет:

> Once again Thank you Andrei.
> Modified the grub source and added grub_exit (). After this BIOS booted
> from next device.
>
> I am now working on a solution where if the UUID present in the grub.cfg
> goes bad.
> One way I am thinking is to check the CRC of the grub.cfg and other image
> files required for booting. This may be bit lengthy.
> Let me know if you have suggestions.
>

grub supports automatic signature verification for files; in case of
mismatch file open fails. Does it help?

> Thanks,
> Subbarao
>
> On Wed, Nov 19, 2014 at 8:57 AM, Venkata Subbarao <
> address@hidden> wrote:
>
> > Thank you very much Andrei.
> > I will try out this and update.
> >
> >
> > - Subbarao
> >
> > On Wed, Nov 19, 2014 at 8:46 AM, Andrei Borzenkov <address@hidden>
> > wrote:
> >
> >> В Tue, 18 Nov 2014 10:51:00 +0000 (UTC)
> >> Venkata Subbarao <address@hidden> пишет:
> >>
> >> > Hi All,
> >> >
> >> > I am working on a task on XUbuntu OS in which due to any reason if
> >> booting
> >> > fails I would like to switch to another boot device by zeroing the MBR
> >> of
> >> > current boot disk. Is this possible ?
> >> >
> >> > For example instead of showing following prompt, I would like to zero
> >> out
> >> > the MBR so that the BIOS can select next boot device upon reset.
> >> >
> >> > error: no such partition
> >> > grub rescue>
> >> >
> >>
> >> grub supports only very limited and controlled ways to write to
> >> device/file. Doing something like this in unattended manner is probably
> >> way too dangerous.
> >>
> >> What would be possible is to optionally exit grub (after timeout) in
> >> this case; then BIOS should proceed to next boot device.
> >>
> >
> >