[Mesa-dev] [PATCH] intel/pre-gen6: Disable EXT_framebuffer_multisample.

Eric Anholt eric at anholt.net
Wed Feb 6 15:03:39 PST 2013


Paul Berry <stereotype441 at gmail.com> writes:

> Previously, the i965 driver enabled EXT_framebuffer_multisample even
> on pre-gen6 chipsets.  However, since we don't support multisampling
> on these chips, we set GL_MAX_SAMPLES=1 (the minimum allowed by
> EXT_framebuffer_multisample), and if the client ever requested a
> multisample buffer, we quietly supplied them with a single-sampled
> buffer instead.
>
> After some discussion on the mailing list (see thread
> "ext_framebuffer_multisample: check for num_samples<=1"), it's clear
> that this was the wrong approach.  The correct approach is to only
> expose EXT_framebuffer_multisample when we truly support
> multisampling; that frees us to set a sensible value of
> GL_MAX_SAMPLES=0 on other chipsets, so that we never have to deal with
> a client requesting a multisample buffer when multisampling isn't
> supported.
>
> This change causes the following piglit tests to be skipped on
> chipsets prior to Gen6:

This looks reasonable to me.  I was worried that we might be breaking
some GL 2.1 functionality (since it has some text about multisample),
but that mostly appears to be effectively about how things work if you
happen to have a multisample window system buffer, which we don't.

Reviewed-by: Eric Anholt <eric at anholt.net>
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