Re: [Qemu-devel] Re: POST failure (loop) with isapc and seabios

[Gleb Natapov]

On Thu, Nov 26, 2009 at 03:12:53AM -0500, Kevin O'Connor wrote:
> > > IMO, migrating to a new bios doesn't make sense - the bios is an
> > > application with state - one can't just replace the code.
> > > 
> > You don't migrate to a new BIOS. You migrate to a new QEMU that happens
> > to have a new BIOS. And ability to migrate to a newer QEMU is a must.
> 
> IMO, the ram at 0xf0000 needs to get migrated just like the rest of
> the ram.
And it is! The old BIOS is running after migration. But on the first reset
after migration new BIOS should be loaded since old one can't initialize
new QEMU any more.

> 
> Silly example - Linux and APM.  On Linux init, it finds the APM
> vectors from bios and periodically calls them to sleep machine.  On
> migration, a new bios could have a different code location for apm -
> if Linux calls sleep after migration it jumps into random code and
> blows up.
> 
That is not silly example. Another example is TPR patching. This examples
shows why old BIOS has to be migrated and used till reboot.

--
                        Gleb.