[Mesa-dev] [PATCH v3 1/2] configure.ac: Enable GLX_USE_TLS if possible.

[tom fogal]

On 02/16/2012 01:57 AM, Zhigang Gong wrote:
>> -----Original Message-----
>> From: tf (mobile) [mailto:tfogal at sci.utah.edu]
>> Sent: Wednesday, February 15, 2012 8:53 PM
>> To: zhigang.gong at linux.intel.com
>> Cc: dbn.lists at gmail.com; nobled at dreamwidth.org;
>> mesa-dev at lists.freedesktop.org
>> Subject: Re: [Mesa-dev] [PATCH v3 1/2] configure.ac: Enable GLX_USE_TLS
>> if possible.
>>
>> Even if the system supports tls, the x server may not have been
>> built with it. As i recall, there is an issue with mismatching tls
>> between x and drivers... Can a non-tls server load a tls driver?
 >
> AFAIK, a mesa built without TLS can work with a xserver built with
> TLS enabled, Actually, this is current situation. Xserver will enable
> TLS if the system support It, but mesa will not enable TLS by default
> no matter the system support it.
>
> IMO, the only relevant part may be the indirect GLX in xserver which
> will load DRI driver and thus mesa. But xserver has its own glapi.c
> and will not share the mesa's glapi.c, then the mismatch will not be
> a big issue. If I missed anything, please correct me.

I think you're forgetting the converse case: when the X server is 
non-TLS and Mesa is.

> Anyway, I still think it's better to keep the xserver and mesa have
> the same configuration when they are built/running on the same
> system. Right?

Yes, I agree.

> Besides that issue, I think mesa should check whether the system
> support TLS and tls model before enable it. So I still want this
> patchset get accepted.
>
> Any comment?

Checking is arguably good.  Auto-enabling is what I really want/like.

I am just relaying the message that there was concern here.  Previously 
there were parties (i.e. Eric on the Mesa side) who were pretty wary of 
said changes.. I tried your patch almost verbatim a while back, before 
implementing this in the X server.  Those parties should be made aware 
this is going in and should give their "LGTM"s.

This is all in the archives.

-tom

>> Anyway, if there's an issue there, this check must be more
>> complicated -- it can't be just, "does the system support this",
>> it would instead need to be "can the system support this and is it
>> enabled in the x server."
>>
>> IIRC Eric and ajax and Dan know more, but there should also be a
>> discussion of this in the xorg-devel and/or mesa archives.
>>
>> -tom
>>
>> On 15.02.2012, at 12:41, zhigang.gong at linux.intel.com wrote:
>>
>>> From: Zhigang Gong<zhigang.gong at linux.intel.com>
>>>
>>> If the system support tls, we prefer to enable it by default just as
>>> xserver does. Actually, the checking code is copied from
>>> xserver/configure.ac.
>>> According to nobled's suggestion, move the checking before
>> enable_asm.
>>> As if tls_model is not supported, then asm may can't work correctly.
>>> Then we check the tls model first, and if doesn't support it, we need
>>> to disable the asm code.
>>> Here is the reference:
>>> https://bugs.freedesktop.org/show_bug.cgi?id=35268