[Mesa-dev] [PATCH 3/3] meson: Only GLX_USE_TLS when glx is in use

[Emil Velikov]

On 19 February 2018 at 18:40, Alexander von Gluck IV
<kallisti5 at unixzen.com> wrote:
> February 19, 2018 12:25 PM, "Alexander von Gluck IV" <kallisti5 at unixzen.com> wrote:
>
>> ---
>> meson.build | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/meson.build b/meson.build
>> index 6fc7ec7fc9..54572a5bb8 100644
>> --- a/meson.build
>> +++ b/meson.build
>> @@ -331,7 +331,6 @@ if with_egl and not (with_platform_drm or with_platform_surfaceless)
>> endif
>> endif
>>
>> -pre_args += '-DGLX_USE_TLS'
>> if with_glx != 'disabled'
>> if not (with_platform_x11 and with_any_opengl)
>> if with_glx == 'auto'
>> @@ -365,6 +364,10 @@ if with_glvnd
>> endif
>> endif
>>
>> +if with_glx != 'disabled'
>> + pre_args += '-DGLX_USE_TLS'
>> +endif
>> +
>> # TODO: toggle for this
>> with_glx_direct = true
>
> Some comments on this one. I was seeing problems loading static TLS binaries
> on Haiku, turns out GLX_USE_TLS impacts more than just GLX. I'm guessing our
> (non-glx) libGL.so is getting it via libglapi linkages.
>
> https://kallisti5.keybase.pub/Screenshots/meson_build_tls.png
>
> Thanks to Dylan for figuring this one out.
>
> This was discussed previously on the ML
> "
> This can be applied to all GLX implementations, and in autotools this is
> guarded only by the --enable-glx-tls flag. Since this is on by default
> in autotools, and is strictly better than being off, the meson build
> doesn't even have a toggle for it.
> "
>
> Since the GLX_USE_TLS reaches beyond GLX, i'm guarding it with_glx after
> the glx auto-detection tri-state (which can disable it)
>
>
Note: the GLX in the name is for historical purposes - toggle applies
to glapi and the way one (GLX, EGL and DRI modules in particular)
makes use of it.

That said - we had serious issues with people tinkering with the
toggle, so Dylan's decision of omit it is spot on.
For Haiku, I would suggest the following:
 - open a bug/other issue about the missing static TLS support
 - set the macro for non-haiku platforms, with a clear reference to
the above report.

> I noticed under Fedora the Meson-built libGL differs from the system's
> in terms of TLS.. not sure if relevant (or an issue)
>
There are a few features missing from the Meson build so I wouldn't be
too surprised.
For now I'd call it a non-issue ;-)

-Emil