Re: [Qemu-devel] [PATCH for-1.5] Revert "pc: Kill the "use flash device for BIOS unless KVM" misfeature"

[Markus Armbruster]

Paolo Bonzini <address@hidden> writes:

> Il 15/05/2013 17:09, Markus Armbruster ha scritto:
>>>>>> @@ -209,7 +209,7 @@ void pc_system_firmware_init(MemoryRegion 
>>>>>> *rom_memory)
>>>>>>       * TODO This device exists only so that users can switch between
>>>>>>       * use of flash and ROM for the BIOS.  The ability to switch was
>>>>>>       * created because flash doesn't work with KVM.  Once it does, we
>>>>>> -     * should drop this device for new machine types.
>>>>>> +     * should drop this device.
>>>>>>       */
>>>>>>      sysfw_dev = (PcSysFwDevice*) qdev_create(NULL, "pc-sysfw");
>>>>>>  
>>>>
>>>> Why did you change the comment?
>>>
>>> Because we agreed on the way forward for the flash patches, and it will
>>> remove the need for (a) changes to machine types; (b) pc_sysfw in
>>> general.  The device will be created iff a -pflash or -drive if=pflash
>>> option is provided.  Thus in principle you could use -M pc-0.12 with
>>> -pflash and it will work.
>> 
>> Yes, that's the way forward, and yes, that means we'll have no use for
>> the "pc-sysfw" dummy device on new machine types.  But why can we
>> retroactively delete it from existing machine types?
>
> Because it would only affect TCG and people probably don't care much
> about backwards-compatible machine types with TCG.  I'd rather remove
> the misfeature completely and start from scratch with a sane design, now
> that we have it.

I'm fine with limiting our backward compatibility promise to KVM, I just
didn't expect it.