On Mon, 2008-09-29 at 14:28 -0700, Jeremy Fitzhardinge wrote:

quoted text
> > Unless there is a central authority assigning these, "we" can do all

> > we want, enough people will not pay attention.

> >

> > Basically, there needs to be a standards document that describes the

> > architecture, *and* needs to either have universal buy-in with all the

> > vendors or imposed by an authority with enough clout to do so (Intel

> > might.)

> ...

> I think using fixed offsets is unwise, since there's already contention

quoted text
> for the same leaves.  Making sure that each block of leaves (where a

> block is 16, 256 or some other number of leaves) is self-describing via

> ABI signatures is the only sane way to go.  There's still the issue of

Aren't we overthinking / overdesigning this a bit?  It's not rocket

science.  We'd like to have a leaf set aside for TSC frequency, and

maybe another leaf in the future.  We think other vendors might find a

static clock frequency leaf to be useful, so if that happens to be the

case, feel free to re-use the leaf.
We don't expect to see lots of proliferation of CPU leaves at all, in

fact, we'd be flummoxed to propose more than one right now.  So

basically a nicely written comment section explaining how the SW CPUID

registers are layed out is probably sufficient.  Other vendors can add

to it as they see fit, and Linux itself can be the central standard

body.  After all, it's what we all work on, and it makes sense for

everyone here, even MS, to have the software leaves defined in a public

work.
The whole thing is software defined so it's not a big deal if one or all

parties eventually don't play well with others, grow up to become

bullies with ADD, or simply autistic children who ignore the whole

thing.  You can always make detection vendor dependent when that

happens.
Right now there's nothing shockingly vendor dependent, just a whole lot

of complicated proposals about how to define what the bits are going to

define and not enough bits of information to actually express.  It seems

perfectly okay for now to have new leaf proposals defined by fiat for

now.
As long as there is a vendor-ID leaf, nobody is blocking any forward

progress by adding a new non-conflicting leaf.  We can always add the

meta-leafs required for decoding if something tangible materializes, but

for now the TSC leaf seems pretty useful and I would probably want to

proclaim it by fatwa, if I had such a power.
Zach
--

unsubscribe notice
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in

the body of a message to majordomo@vger.kernel.org

More majordomo info at  http://vger.kernel.org/majordomo-info.html

Please read the FAQ at  http://www.tux.org/lkml/