Re: [PATCH 00/23] Add KVM support for PPC64 (970) hosts

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Tue, 2009-07-07 at 17:49 +0200, Alexander Graf wrote:
> I'm completely open to naming suggenstions. The code is 100% ppc64  
> compatible. I'm not aware of any 970 specifics. I just thought all  
> PPC64 cores are called something with 970.

 :-)

So 970 is just the thing also known as G5 which is a "light" variant of
the POWER 4 processor.

Basically, the world we support in linux looks like that:

 - Power3 and rs64: We really don't want to deal with these for now.
They don't have SLBs for example, but instead some more ancient stuff
call stab etc... besides they are old stuff.

 - Power4: First one with an SLB, no altivec (aka VMX). Only older IBM
server machines. The FW on those machines let you operate in "full
system partition" mode (ie, no hypervisor underneath you, ie, you run
with MSR:HV=1) or partitioned, but the partitionning is relatively
simplistic (fixed, no shared processors, etc...)

 - 970 (aka G5, aka GPUL): This is the stuff that was made for Apple
(sort-of), it's derived from some later revision of the Power4,
simplified in some ways, and adds a VMX to it among other things. It was
also used in some IBM products such as the js20 and js21 blades, or in
the Fixstar PowerStation.

 - Power5: Back to IBM "server" processors, this is an
evolution/improvement of Power4. It doesn't have VMX, but brings
multithread (2 threads per core). Also, the FW on those machines never
let you run without the hypervisor underneath you. Later revisions
support 1G segments in the SLB which we may have to emulate if we want
the guest to use them at some stages and supports 64K page sizes.

 - Power6: This adds back VMX, different pipeline structure than Power5
(oriented toward mhz, much more in order, etc...). Current offering.
Also available on js22 blades.

 - Cell: The ppc core in there is simplistic, but supports multithreads
and altivec. It's based on arch 2.02 or so, so it has SLB etc... it
supports also 64K and 1M page sizes under some circumstances (ie, you
can only enable 2 out of the 3 non-4K sizes via some HID bits or on PS3,
some HV calls) but doesn't support 1G segments. Of course, it adds SPUs
but that's out of the core.

And that's about all we can talk about at this stage :-) I think there
have been patches posted already related to Power7 but I don't know how
much we can or cannot tell about it, though from your POV it shouldn't
be very different from P5 or P6.

Cheers,
Ben.