Re: [PATCH v5 00/19] Make Pixman an optional dependency

[Thomas Huth <thuth@redhat.com>]

On 24/10/2023 14.01, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Oct 23, 2023 at 5:49 PM <marcandre.lureau@redhat.com> wrote:
>>
>> From: Marc-André Lureau <marcandre.lureau@redhat.com>
>>
>> Hi,
>>
>> QEMU system emulators can be made to compile and work without Pixman.
>>
>> Only a few devices and options actually require it (VNC, Gtk, Spice for ex) and
>> will have to be compiled out.
>>
>> However, most of QEMU graphics-related code is based on pixman_image_t and
>> format. If we want to provide mostly compatible QEMU machines with or without
>> Pixman, all we need to do is to have a small compatibility header with just the
>> bare minimum for those types (see "ui: add pixman-compat.h"). There are a
>> limited number of operations related to geometry that are slightly better
>> implemented in QEMU (without Pixman, see "virtio-gpu: replace PIXMAN for
>> region/rect test").
>>
>> Without this simple compatibility header approach, QEMU at runtime becomes a
>> very different emulator (without graphics device/board, display etc) and full of
>> "if PIXMAN" conditions in the code. This is a much worse outcome imho, compared
>> to this small header maintainance and compatibility story.
>>
>> Fixes:
>> https://gitlab.com/qemu-project/qemu/-/issues/1172
> 
> Before I send v6 with minor changes, do we have a consensus on the
> approach using the small pixman-compat.h header to keep 99%
> compatibility with a qemu compiled with pixman and minimal changes?

It looks reasonable to me - at least for a first step, since it's not a very 
huge change. We still can change it easily later if we reconsider, I guess.

  Thomas