Hi Duncan,
I haven't been paying much attention to mesa or X11 for a few years. I'm just
now looking back since I have some free cycles on vacation. I see you did some
work in https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28205 to get
darwin/x11 to use gallium, but the way we go about it with macro definitions is
quite confusing to me since we end up having macros that seem not well defined
any more
Previously, GLX_USE_APPLEGL=1 meant "build a hacky libGL from the mesa sources
in a mostly nonstandard way since we never got around to merging things
together to make the implementation selectable at runtime" and
GLX_USE_APPLEGL=0 meant "build a modern gallium libGL that you can use for
swrast or IGLX but that doesn't work with hardware acceleration because we
never got around to moving glx/apple into the modern era. What does
GLX_USE_APPLEGL mean now?
With the introduction of GLX_USE_APPLEGL=1 GLX_USE_APPLE=1, it seems that we're
getting gallium but with some slight differences from the GLX_USE_APPLEGL=0
case.
Relatedly, is GLX_USE_APPLEGL=0 GLX_USE_APPLE=1 expected to be a valid
configuration? If so, what does it mean? It looks like the only difference
between it and GLX_USE_APPLEGL=0 GLX_USE_APPLE=0 is at src/glx/glxext.c:1029:
#if !defined(GLX_USE_APPLE)
if (!dpyPriv->has_multibuffer && glx_accel &&
!debug_get_bool_option("LIBGL_KOPPER_DRI2", false)) {
if (glx_driver & GLX_DRIVER_ZINK_YES) {
CriticalErrorMessageF("DRI3 not available\n");
goto init_fail;
}
glx_driver &= ~GLX_DRIVER_ZINK_INFER;
}
#endif
which seems maybe not intentional ... ? Why would we want that for
GLX_USE_APPLEGL=1 GLX_USE_APPLE=1 but not GLX_USE_APPLEGL=1 GLX_USE_APPLE=0?
So I'm confused as to why we need two variables here. I'd like to get us down
to 0, whereby the OpenGL.framework backend is selectable at runtime rather than
build time, and these changes you've made seem to make the build space a bit
more complicated than they were before.
Can you walk me through the design decisions here? I'd be happy to chat over
Webex / Zoom / whatever if that would be easier.
Thanks,
Jeremy
