[Mesa-stable] [PATCH (10.6)] egl/dri2: implement platform_surfaceless

[Mark Janes]

Emil Velikov <emil.l.velikov at gmail.com> writes:

> Hi all,
>
> On 25 August 2015 at 18:09, Chad Versace <chad.versace at intel.com> wrote:
>> From: Haixia Shi <hshi at chromium.org>
>>
>> The surfaceless platform is for off-screen rendering only. Render node support
>> is required.
>>
>> Only consider the render nodes. Do not use normal nodes as they require
>> auth hooks.
>>
>> v3: change platform_null to platform_surfaceless
>> v4: make libdrm required for surfaceless
>> v5: remove modified include guards with defined(HAVE_SURFACELESS_PLATFORM)
>> v6: use O_CLOEXEC for drm fd
>>
>> Cc: "10.6" <mesa-stable at lists.freedesktop.org>
>> Cc: Mark Janes <mark.a.janes at intel.com>
>> Signed-off-by: Haixia Shi <hshi at chromium.org>
>> Signed-off-by: Zach Reizner <zachr at google.com>
>> Reviewed-by: Emil Velikov <emil.l.velikov at gmail.com>
>> Reviewed-by: Chad Versace <chad.versace at intel.com>
>> (cherry picked from commit 6b8accb36b541f77774109ea42533c02bb90bc68)
>> ---
>>
>> This is a cherry-pick of EGL's surfaceless backend to the 10.6 branch.
>> If upstream 10.6 included this feature, that would make validation
>> easier for several groups inside Intel (and probably Google too).
>>
>> I think this is safe to cherry-pick into a stable release because it
>> will have zero impact on stability:
>>
>>   - The feature isn't enabled (or even compiled into libEGL) unless it's
>>     explicitly enabled at configure time.  In other words, this
>>     cherry-pick will add no new feature to distro Mesa packages.
>>
>>   - The patch's changes are largely self-contained and confined to a new
>>     file (platform_surfaceless.c). That file is built only if the
>>     feature is enabled at configure time.
>>
>>   - Changes to existing source files are minimal (+/- 14 lines) and
>>     safe. They consist of adding the new enum _EGL_PLATFORM_SURFACELESS
>>     and some code that switches on it.
>>
>> I understand there's not much precedent for adding patches like this to
>> a stable branch. So my feelings won't get hurt if the patch is rejected.
>>
> I'm a bit ambivalent about this bth.
>
> On one hand it's nicely isolated from everything else, requires
> additional configure switch and even an env variable to get it running
> (EGL_*_platform_surfaceless anyone ?). On the other hand it's never a
> good idea to add new features (platform support in this case) in
> bugfix releases esp this late on. The fact that there is no upstream
> user for it (that I know of) doesn't make it much better :'(

I'd like to run dEQP on a daily basis, to catch any regressions in 10.6.
Because my test system has no X, I need the surfaceless patches.

> I'm be ok with pulling this, if we get a positive response from other
> (non intel/google) team/developer.
>
> Having someone spend a few minutes to remove (or forward to the ML)
> the 40 or so patches in the chromiumos tree could also help ;-)
>
> Thanks
> Emil
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