Re: [Qemu-stable] [Qemu-devel] [PATCH for-1.4 0/2] fix migration failure from 1.3 due to SeaBIOS size change

[Anthony Liguori]

"Michael S. Tsirkin" <address@hidden> writes:

> On Tue, Feb 05, 2013 at 09:08:20PM -0600, Anthony Liguori wrote:
>> Michael Roth <address@hidden> writes:
>> 
>> > Migration from 1.3 currently fails due to a mismatch between the expected 
>> > size
>> > of 256KB and the received size of 128KB for seabios. This series attempts 
>> > to
>> > fix the issue by allowing a resize function to be registered to handle 
>> > resizing
>> > memory blocks to accomodate the source's, and using that to re-initialize
>> > "pc.bios" and "isa-bios" MemoryRegions based on the size of the incoming 
>> > block.
>> >
>> > There are also 2 potential alternatives to this patch set:
>> >
>> > 1) When I compile seabios 1.7.2 locally I end up with a 128KB binary.
>> 
>> So do I on Fedora 18.  Unless someone has a reason why this is a bad
>> thing, I'll commit a 128kb binary and we can avoid this problem for 1.4.
>> 
>> Obviously, we need to figure it out but that at least buys us some time...
>> 
>> Regards,
>> 
>> Anthony Liguori
>
> So we never bothered with this patch, and so it's still out.
> How about we apply this for 1.5?

This problem occurred because Gerd built SeaBIOS on RHEL6.x which
resulted in a 256k binary.

On F18, we're still fitting in 128k.  There is no reason to worry about
BIOS size right now.

At some point, we will need to split into two separate BIOSes--a 128Kb
and a 256Kb.  This can be handled by having two SeaBIOS configuration
files where one has a reduced feature set.

We then would create an i440fx property that selects either the 128Kb or
256Kb BIOS.  This property can then be setup as part of machine globals.

So -M 1.4  or -M 1.5 will always use a 128Kb BIOS.  If we need to, 1.6
may end up with a 256Kb BIOS.

> This way we, at least, won't have the problem with -M1.5 in the future.
> Barring that - early in 1.6 cycle?

The problem with Mike's patch is that it only solves older -> newer.
The solution I outlined above also works for newer -> older.

Regards,

Anthony Liguori
>
> -- 
> MST