[SeaBIOS] [PATCH 2/2] accept MADT over fw_cfg

[Paolo Bonzini]

Il 21/03/2013 14:12, Michael S. Tsirkin ha scritto:
> On Thu, Mar 21, 2013 at 01:04:35PM +0000, David Woodhouse wrote:
>> On Thu, 2013-03-21 at 13:56 +0100, Laszlo Ersek wrote:
>>> - for an earlier qemu, the option must be set,
>>> - for a later qemu the option must be clear &&
>>>   (no -acpitable switch must be specified on the qemu cmldine ||
>>>    one -acpitable switch must load a MADT)
>>
>> Hm, that sounds like it won't be possible to build one version of
>> SeaBIOS that works for *both* old and new qemu. That doesn't seem like a
>> great idea. I'd prefer something like:
>>
>> - If Qemu provides the 'core' ACPI tables (i.e. not just SSDT) then 
>>   SeaBIOS uses them.
>> - Otherwise, it makes its own.
>>
>>
>> -- 
>> dwmw2
> 
> It might simplify life for someone bisecting qemu
> as you don't need to rebuild seabios after each
> bisect but is this really a common workflow?

It would help me working on RHEL's qemu-kvm, which I often do on a
Fedora box.

The bios.bin in the RHEL qemu-kvm tree is obsolete (like Gerd showed for
Fedora, RHEL's bios.bin comes from a separate package), and using
whatever happens to be in /usr or in my local SeaBIOS clone is the
simplest thing to do.  I'd like this not to break.

Paolo

> Anyway, I am not against such runtime flags.
> 
> If we add to this an option to build a minimal BIOS
> that only works with the new QEMU, do we have a deal?
> 
> Then the plan is to make progress and apply patches step by step without
> deciding on the detection interface first.
> Before QEMU is switched to the new configuration,
> we'll add the runtime thing for the benefit of developers
> that bisect.
> 
> Makes sense?
>