Re: [oe] [RFC] OpenGL packaging/staging policy

[Otavio Salvador <otavio@ossystems.com.br>]

On Mon, Oct 22, 2012 at 3:32 PM, Phil Blundell <philb@gnu.org> wrote:
> On Mon, 2012-10-22 at 17:35 +0100, Burton, Ross wrote:
>> Rule 3. Only Mesa stages, nothing else
>>
>> Whilst there are multiple GL implementations that offer various
>> subsets of GL, they are all effectively interchangeable.  It's not a
>> massive concern what exact GL is present when building because they've
>> all got the same API.
>
> This is an attractive idea but I'm not sure that the underlying
> assumption is entirely correct.
>
> Different GL libraries will have different vendor extensions and Mesa's
> headers won't necessarily know about them.  If the vendor ships the
> extension bits in a custom header (rather than jamming them into a
> modified glext.h) then this could be worked around by staging the
> headers separately, but you're still left with the problem that Mesa's
> libGL.so might now be missing symbols that are required during
> linking.
>
> Also, even if the APIs were the same, I am slightly nervous about
> relying on all vendor GLs having an identical ABI to Mesa.  I can't
> immediately think of any reason why they shouldn't but, equally, vendors
> have been known to do peculiar things in the past and I wouldn't be
> totally shocked to find that there is some binary libGL out there which
> manages to be ABI-incompatible with Mesa in some or other creative
> fashion.

In this case every package depending on GL packages will be
PACKAGE_ARCH specific; this would be nice if we can share it amoung
boards at least.

-- 
Otavio Salvador                             O.S. Systems
E-mail: otavio@ossystems.com.br  http://www.ossystems.com.br
Mobile: +55 53 9981-7854              http://projetos.ossystems.com.br