[Qemu-devel] Re: [SeaBIOS] [PATCH 0/8] option rom loading overhaul.

[Anthony Liguori]

Gleb Natapov wrote:
> > More importantly though, what's the use-case here?
> >
> >     
> Use-case for what? This just what need to be done for correct HW
> emulation.
>   

Live migration is transparent to the guest.  The fact that firmware can 
upgrade itself without the guest doing anything is not something that 
really has a real world equivalent.

Even if it did, whether that automatic upgrade happens after a reboot 
vs. a hard power cycle is irrelevant.  The guest has no knowledge of the 
fact that the automatic firmware upgrade happened so if it gets delayed 
indefinitely, it doesn't matter.

It's not a matter of correctness IMHO.

I can understand an argument for predictability wrt wanted to be able to 
guarantee that after the first reboot during a live migration, you'll 
get the new firmware.  I'm not sure that's less predictable then hard 
shutdown/start-up and I'm not sure I can really make an argument for one 
way vs. the other.

If anything, I can better understand the argument for not ever upgrading 
the firmware transparently.  Something like having a nvram file that we 
load all of the ROMs into, then do live migration and migrate the nvram 
file.  That would mean that we would have to be very careful in the 
future about supporting fw_cfg as a versioned interface.

We would also want to provide a mechanism for a user to manually upgrade 
the firmware from within a guest if we went this route.

Regards,

Anthony Liguori