On 9/14/20 10:13 PM, Jim Mattson wrote:
On Mon, Sep 14, 2020 at 5:18 PM Jim Mattson <jmattson@xxxxxxxxxx> wrote:
On Fri, Sep 11, 2020 at 8:36 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
On 31/08/20 23:55, Jim Mattson wrote:
Moreover, older AMD hardware never sets bits 32 or 33 at all.
Interesting, I didn't know this. Is it documented at all?
You'll have to find an old version of the APM. For example, see page
56 of https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.0x04.net%2Fdoc%2Famd%2F33047.pdf&data=02%7C01%7Cthomas.lendacky%40amd.com%7C9ee685813f444f314d4808d859255108%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637357364669001358&sdata=3a%2F0OrkZHC7r8vsoq2yhKqt8cQ8siPt6PG%2Be674yiXs%3D&reserved=0 (this was back when SVM
was a separate document).
Ah ha. It looks like bits 32 and 33 weren't there in version 3.14 of
the APM volume 2 in September 2007. (See
https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fapplication-notes.digchip.com%2F019%2F19-44680.pdf&data=02%7C01%7Cthomas.lendacky%40amd.com%7C9ee685813f444f314d4808d859255108%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637357364669001358&sdata=iZ0lotbZ4kRtRrjE9bVb%2F9NSy7H3RMJauUfe3FvGDT0%3D&reserved=0, pages 410-411.)
They had appeared by version 3.17 in June 2010. Maybe someone from AMD
can enlighten us. My memory's just not that good.
I tried to do some digging on it. It looks like the support was available
back in fam14h. Not sure about families before that. It would have been
nice to have a CPUID bit for this.
Thanks,
Tom
