Re: [Qemu-devel] [RfC] using pixman in qemu for raster ops

[Gerd Hoffmann <kraxel@redhat.com>]

On 09/25/12 11:31, Peter Maydell wrote:
> On 25 September 2012 09:47, Gerd Hoffmann <kraxel@redhat.com> wrote:
>> Even though pixman is used by core linux packages it is still a young
>> project. On older distros (RHEL-5 for example) it isn't included and
>> must be compiled manually.
> 
> For me "not a standard library package on RHEL5" is a strong argument
> against adding a hard dependency. (For instance, most of the compute
> cluster machines here are RHEL5 and it would be pretty awkward to
> deal with manually building a dependent library.)

Why it is that a big deal?  Whatever is used to distribute qemu to the
cluster machines (local yum repo?) can be used to distribute pixman too, no?

I rarely found a piece of software which builds as easy as pixman.  No
unusual dependencies.  No tricks stuff in the specfile.  You can grab as
source rpm from rhel6 or fedora, rebuild it for rhel5 and be done with
it.  Backports on other distros should likewise be simple.

> So they're a new library -- how good are they at API/ABI stability?

I didn't notice any issues until now (didn't search though).  No soname
bump yet.  And given Xorg + cairo are using pixman they hardly can get
it wrong unnoticed, things would break left+right all over the place if
they did.

> I also note that http://pixman.org/ says "There is currently no
> documentation besides the source code itself", which makes me
> really really wary of using it.

That made me worry too, but it was surprisingly easy to get along with
just the header file and some sample code.  At the end of the day it is
just standard raster ops and transformations built into a library.

cheers,
  Gerd