[Mesa-dev] S2TC - yet another attempt to solve the "S3TC issue"

Jose Fonseca jfonseca at vmware.com
Sun Aug 7 18:48:39 PDT 2011

----- Original Message -----
> On Wed, Aug 03, 2011 at 12:47:47PM -0700, Ian Romanick wrote:
> > Hash: SHA1
> > 
> > On 08/03/2011 12:11 PM, Bryan Cain wrote:
> > > On 08/03/2011 01:58 PM, Ian Romanick wrote:
> > >> I think this solves the issue for the compressor and for the
> > >> software
> > >> decompressor.  I don't think this solves the problem for the
> > >> decompressor for hardware drivers, so that may still pose a
> > >> problem for
> > >> Linux distros.
> > > 
> > > Pardon my ignorance, but why do hardware drivers need a
> > > decompressor?
> > 
> > To quote the EXT_texture_compression_s3tc spec:
> > 
> >     WARNING:  Vendors able to support S3TC texture compression in
> >     Direct3D
> >     drivers do not necessarily have the right to use the same
> > functionality in
> >     OpenGL.
> > 
> > This is the same issue that Linux distros have with
> > ARB_texture_float
> > being enabled in hardware drivers.  The hardware may implement the
> > functionality, and the hardware vendor may have some license for
> > the
> > patent, but that license may not cover making the functionality
> > available in Mesa.  That S3 has sued Apple is some indication that
> > these
> > licenses may have very narrow scope.

> Why should exactly Mesa be the one to have IP rights then? Mesa
> doesn't feed
> S3TC data anywhere, when using S2TC or another alternative.

> Feeding self-compressed S2TC data is no issue, as it doesn't use any
> of the
> S3TC IP. How the GPU actually decodes it, is none of Mesa's business.

It's not black and white: there can be both direct and indirect infringement on certain certain countries.  Please read patent law and/or contract a real lawyer.

> Feeding precompressed data, however, is also none of Mesa's business
> - and
> also, Mesa ALREADY does this, so if it's illegal, that's a risk Mesa
> already is
> taking. 

False.  Mesa does NOT already do this.  It needs an additional component to enable S3TC, which is clearly marked as third-party IP sensitive, and advise people to contact a lawyer or obtain a license.

So please stop making false accusations.

> However, Mesa doesn't know if it's feeding S3TC or S2TC data
> - it feeds
> a data block as is. So, if anyone needs IP rights then, it's the
> author of the
> game that comes with precompressed S3TC textures - and not the
> graphics driver!

More conclusions based on false premises...

> At least that's my opinion (IANAL too).

Don't get me wrong, I think S2TC's an interesting piece of work, but how do you dare to presume to tell us what we should or should not do in legal matters, while claiming to not be a lawyer, nor offering to pay legal expenses resulting from following your advice?  You must think really highly of yourself, or think we are really dumb to not have thought/discussed this till now.

We need this sort of "IANAL" opinions just as much as we need chronic tooth pain.


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