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Subject: Re: Probing for native availability of isel from userspace
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From: Kumar Gala <galak@kernel.crashing.org>
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Date: Tue, 25 Sep 2012 19:17:58 -0500
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To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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On Sep 25, 2012, at 3:59 PM, Benjamin Herrenschmidt wrote:

> On Tue, 2012-09-25 at 15:17 +0200, Segher Boessenkool wrote:
>>>> Fine. But I believe that mfpvr emulation came first, which is the =20=

>>>> point
>>>> I object to (see the mess that the fact that CPUID is available to
>>>> applications made to x86 when SSE registers were added).
>>>=20
>>> Heh, possibly, I don't remember... I added the cputable, I think we
>>> added mfpvr because we didn't have anything, then I added cputable =20=

>>> which
>>> got us the HW caps, but some old stuff still relied on mfpvr so we
>>> couldn't completely remove it.
>>=20
>> If I have my history right end up, MFPVR emulation was added for MoL.
>> Which is funny (if you like that kind of thing) because it now hurts
>> all other "hypervisor in userspace" kind of things, that might want
>> to lie in their emulated PVR...
>=20
> Are you sure ? MOL had a kernel module, it wouldn't have needed =
that...

I feel like there was some JVMs (IBMs?) that used MFPVR to determine =
some things.

- k=