Re: Athlon 64 X2 cpuinfo oddities

[Jesper Juhl <jesper.juhl@gmail.com>]

On 10 Jan 2006 02:49:13 +0100, Andi Kleen <ak@suse.de> wrote:
> Jesper Juhl <jesper.juhl@gmail.com> writes:
> >
> > Well, first of all you'll notice that the second core shows a
> > "physical id" of 127 while the first core shows an id of 0.  Shouldn't
> > the second core be id 1, just like the "core id" fields are 0 & 1?
>
> In theory it could be an uninitialized phys_proc_id (0xff >> 1),
> but it could be also the BIOS just setting the local APIC of CPU 1
> to 0xff for some reason.
>
> If you add a printk("PHYSCPU %d %x\n", smp_processor_id(), phys_proc_id[smp_processor_id()])
> at the end of arch/x86_64/kernel/setup.c:early_identify_cpu() what does
> dmesg | grep PHYSCPU output?
>
Not a thing since I'm using arch/i386 here (32bit distribution
(Slackware), just building a 32bit kernel optimized for K8).
But, I stuck that printk into identify_cpu() in
arch/i386/kernel/cpu/common.c instead, and this is what I get :
$ dmesg | grep PHYSCPU
[   30.323965] PHYSCPU 0 0
[   30.402588] PHYSCPU 1 7f


> >
> > Second thing I find slightly odd is the lack of "sse3" in the "flags" list.
> > I was under the impression that all AMD Athlon 64 X2 CPU's featured SSE3?
> > Is it a case of:
> >  a) Me being wrong, not all Athlon 64 X2's feature SSE3?
> >  b) The CPU actually featuring SSE3 but Linux not taking advantage of it?
> >  c) The CPU features SSE3 and it's being utilized, but /proc/cpuinfo
> > doesn't show that fact?
> >  d) Something else?
>
> It's called pni (prescott new instructions) for historical reasons. We added
> the bit too early before Intel's marketing department could make up its
> mind fully, so Linux is stuck with the old codename.
>
Does anything actually parse the /proc/cpuinfo flags field? are we
really stuck with it?
Ohh well, no big deal.


--
Jesper Juhl <jesper.juhl@gmail.com>
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