[Qemu-devel] feature request: changing boot device in the monitor

[Qemu-devel] feature request: changing boot device in the monitor

[Gildas]

Hi,

I don't know whether this is an easy one or not and if it will apply
to all archs, but I'd like to see an option in the monitor to
change/override the value given for -boot.

This way, for instance if you install a VM from a CDROM using "-boot
d", you would be able to restart it on the hard-drive from the monitor
with something like "boot c" followed by "system_reset".

I know there is still the workaround of stopping the emulation and
restarting it with a different set of commands, but when remotely
accessing a VM with a lots of redirection/connection, it's not very
handy.

Of course there is also an orthogonal way of doing this consisting in
adding a boot menu to the BIOS. Implementing both ways would of course
be nice, but the monitor solution would have my preference :)

Regards,
Gildas

Re: [Qemu-devel] feature request: changing boot device in the monitor

[Daniel P. Berrange]

On Mon, Dec 03, 2007 at 01:34:16PM +0000, Gildas wrote:
> Hi,
> 
> I don't know whether this is an easy one or not and if it will apply
> to all archs, but I'd like to see an option in the monitor to
> change/override the value given for -boot.
> 
> This way, for instance if you install a VM from a CDROM using "-boot
> d", you would be able to restart it on the hard-drive from the monitor
> with something like "boot c" followed by "system_reset".
> 
> I know there is still the workaround of stopping the emulation and
> restarting it with a different set of commands, but when remotely
> accessing a VM with a lots of redirection/connection, it's not very
> handy.
> 
> Of course there is also an orthogonal way of doing this consisting in
> adding a boot menu to the BIOS. Implementing both ways would of course
> be nice, but the monitor solution would have my preference :)

There's a patch for this floating around.

http://www.mail-archive.com/kvm-devel@lists.sourceforge.net/msg06675.html

We use it in KVM / Xen on Fedora. Not sure offhand if Bochs project ever
accepted the patch in their upstream for the BIOS.

Dan.
-- 
|=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 978 392 2496 -=|
|=-           Perl modules: http://search.cpan.org/~danberr/              -=|
|=-               Projects: http://freshmeat.net/~danielpb/               -=|
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Re: [Qemu-devel] feature request: changing boot device in the monitor

[Gildas]

2007/12/3, Daniel P. Berrange <berrange@redhat.com>:
> On Mon, Dec 03, 2007 at 01:34:16PM +0000, Gildas wrote:
> > Hi,
> >
> > I don't know whether this is an easy one or not and if it will apply
> > to all archs, but I'd like to see an option in the monitor to
> > change/override the value given for -boot.
> >
> > This way, for instance if you install a VM from a CDROM using "-boot
> > d", you would be able to restart it on the hard-drive from the monitor
> > with something like "boot c" followed by "system_reset".
> >
> > I know there is still the workaround of stopping the emulation and
> > restarting it with a different set of commands, but when remotely
> > accessing a VM with a lots of redirection/connection, it's not very
> > handy.
> >
> > Of course there is also an orthogonal way of doing this consisting in
> > adding a boot menu to the BIOS. Implementing both ways would of course
> > be nice, but the monitor solution would have my preference :)
>
> There's a patch for this floating around.
>
> http://www.mail-archive.com/kvm-devel@lists.sourceforge.net/msg06675.html
>
> We use it in KVM / Xen on Fedora. Not sure offhand if Bochs project ever
> accepted the patch in their upstream for the BIOS.
>
> Dan.
> --
> |=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 978 392 2496 -=|
> |=-           Perl modules: http://search.cpan.org/~danberr/              -=|
> |=-               Projects: http://freshmeat.net/~danielpb/               -=|
> |=-  GnuPG: 7D3B9505   F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505  -=|

Hi Daniel,

Thanks for the link. I somehow managed not to see it.

For the record, there's a later version of the patch in the same thread:
http://www.mail-archive.com/kvm-devel@lists.sourceforge.net/msg07058.html
Which version do you include in Fedora?

As far as I can tell, none of the patches were applied to the
mainstream bochs rombios.c.

Since qemu is shipped with a binary bios image and a diff set for
bochs' bios, can this patch be added to qemu's diff set and included
in the default bios?

Regards,
Gildas

Re: [Qemu-devel] feature request: changing boot device in the monitor

[Dan Kenigsberg]

On Mon, Dec 03, 2007 at 01:34:16PM +0000, Gildas wrote:
> Hi,
> 
> I don't know whether this is an easy one or not and if it will apply
> to all archs, but I'd like to see an option in the monitor to
> change/override the value given for -boot.
> 
> This way, for instance if you install a VM from a CDROM using "-boot
> d", you would be able to restart it on the hard-drive from the monitor
> with something like "boot c" followed by "system_reset".
> 
> I know there is still the workaround of stopping the emulation and
> restarting it with a different set of commands, but when remotely
> accessing a VM with a lots of redirection/connection, it's not very
> handy.

And there's another workaround: you can now start qemu with -boot dc , do
your thing with the cd image, go to monitor, eject the cd, and
system_reset. This time, since there's no cd, the bios will boot from
the hard drive. Just as it happens in OS installation on real hardware.

Dan.

Re: [Qemu-devel] feature request: changing boot device in the monitor

[Gildas]

2007/12/3, Dan Kenigsberg <danken@qumranet.com>:
> On Mon, Dec 03, 2007 at 01:34:16PM +0000, Gildas wrote:
> > Hi,
> >
> > I don't know whether this is an easy one or not and if it will apply
> > to all archs, but I'd like to see an option in the monitor to
> > change/override the value given for -boot.
> >
> > This way, for instance if you install a VM from a CDROM using "-boot
> > d", you would be able to restart it on the hard-drive from the monitor
> > with something like "boot c" followed by "system_reset".
> >
> > I know there is still the workaround of stopping the emulation and
> > restarting it with a different set of commands, but when remotely
> > accessing a VM with a lots of redirection/connection, it's not very
> > handy.
>
> And there's another workaround: you can now start qemu with -boot dc , do
> your thing with the cd image, go to monitor, eject the cd, and
> system_reset. This time, since there's no cd, the bios will boot from
> the hard drive. Just as it happens in OS installation on real hardware.
>
> Dan.

Nice trick. Still a "boot" option in the monitor would be nicer/more
flexible, so if someone feel like implementing this feature... :)

Gildas