Re: [Qemu-devel] [RFC PATCH] Allow building without graphics support

[Alexander Graf]

On 13.12.2012, at 16:16, Gerd Hoffmann wrote:

>  Hi,
> 
>>> A pretty central data structure in qemu (DisplayState /
>>> DisplaySurface) carries a pixman image, not some module which can
>>> easily be made optional.  Just look at the tons of #ifdef'ery you
>>> have to do to get this going.
>> 
>> His point is that anything related to DisplayState should be
>> optional.
> 
> We can try, but sprinkling #ifdefs all over the place isn't the way to
> go.  Separate any Display* stuff, say to display.[ch].  Include
> display.h only when needed.  Then not compiling the object files
> will do the trick, and maybe one or two #ifdefs in vl.c.
> 
> At least in theory.  In practice it probably needs some more cleanups so
> it actually works.
> 
> And the "not compiling" part brings us back to the "easy way to strip
> down qemu" part.  I'd love to have something (kconfig?) which allows to
> pick which device emulations, block formats, ... I wanna include into qemu.

I 100% concur. I was merely trying to make sure we're all on the same page :).

> 
>>> Oh, using pixman will actually make the qemu binaries smaller as we
>>> can replace code with library calls.
> 
>> That doesn't help for the full system load. We're talking of flash
>> chips in the MB range with an embedded initrd here, so you'd have to
>> factor in pixman as well, as without QEMU there wouldn't be a pixman
>> in the system in the first place.
> 
> Most systems have pixman anyway, but yes I can see embedded being different.
> 
>> For the time being, almost none of my boxes can compile QEMU anymore.
>> I have pixman versions
>> 
>> 0.12.0 0.16.0 0.16.4 0.26.0
> 
> Dunno about 0.12 (see other mail), but 0.16+ should be fine (once the
> pending patch is updated and committed).

Yeah, though I'd really prefer if we do the configure check based on features, 
not based on versions. That way backports for example would work.


Alex