Re: [Qemu-devel] [PATCH][RFC] Split non-TCG bits out of exec.c

[Anthony Liguori <anthony@codemonkey.ws>]

andrzej zaborowski wrote:
> 2008/11/13 Anthony Liguori <anthony@codemonkey.ws>:
>   
>> andrzej zaborowski wrote:
>>     
>>> Is this going a bit in the opposite direction to where QEMUAccel is
>>> going?  What Fabrice suggests seems to be like QEMUAccel, with TCG
>>> treated as another accelerator.
>>>
>>>       
>> QEMUAccel is a bit orthogonal to what I'm talking about.  There is already
>> KVM support in QEMU today and I'm merely looking to restructure existing
>> code so that I can build a version of QEMU that has no TCG support, only KVM
>> support.  TCG is too intimately woven into QEMU right now.  You could think
>> of this perhaps as a precursor to making TCG more of an "accelerator" than
>> it is today.
>>     
>
> Ah, I agree with your patch, I was only commenting on the idea of
> *-kvm/ targets.  I see something like QEMUAccel as a way to turn on
> and off the cpu emulators (TCG, kvm, kqemu).

The issue is not disabling TCG at runtime.  That's easy enough.  The 
issue is that TCG doesn't exist (and probably won't ever exist) for 
certain architectures like ia64 and s390.  Being forced to build with 
TCG support makes having QEMU + KVM not possible on these platforms even 
though they both support KVM.

The idea behind a -kvm target is to be able to use QEMU + KVM on these 
architectures in a clean way.  We could also build qemu-system-s390 and 
just exclude TCG but from a naming perspective, it makes sense to be 
qemu-kvm because there can only be a single KVM executable for any given 
platform.

Regards,

Anthony Liguori