Re: RFC: top level compatibles for virtual platforms

On Mon, Jul 11, 2011 at 11:34 PM, Yoder Stuart-B08248
[off-list ref] wrote:

quoted

-----Original Message-----
From: Tabi Timur-B04825
Sent: Friday, July 08, 2011 8:39 PM
To: Yoder Stuart-B08248
Cc: Grant Likely; Benjamin Herrenschmidt; Gala Kumar-B11780; Wood Scott-=

B07421; Alexander

quoted

Graf; linuxppc-dev@ozlabs.org
Subject: Re: RFC: top level compatibles for virtual platforms

On Fri, Jul 8, 2011 at 1:43 PM, Yoder Stuart-B08248 <B08248@freescale.co=

m> wrote:

quoted

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=A0 "MPC85xxDS" - for a virtual machine for the e500v2 type platforms
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 and would support 85xx targets, plus P=

2020, P1022,etc

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=A0 "corenet-32-ds" - for a virtual machine similar to the 32-bit P408=

0

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=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 platforms

=A0 "corenet-64-ds" - for a virtual machine based on a 64-bit corenet
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 platform

I think we should drop the "DS" because that's a name applied to certain=

 Freescale reference

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boards.

Is being a CoreNet board really something meaningful with respect to KVM=

? =A0I don't see the

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connection.

We're talking about what would be meaningful to Linux as a guest on
this platform here-- =A0Corenet-based SoCs are similar
in various ways, like using msgsnd for IPIs, having external proxy
support, etc.

A corenet platform created by a QEMU/KVM looks similar
to other corenet SoCs. =A0 So, I'm trying to find some generic
compatible string that describes this platform.

quoted

Also, if these are KVM creations, shouldn't there be a "kvm" in the comp=

atible string

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somewhere?

There is nothing KVM specific about these platforms. =A0Any hypervisor
could create a similar virtual machine.

A guest OS can determine specific info about the hypervisor it is
running on by looking at the /hypervisor node on the device
tree.

We could put a generic -hv extension to indicate that this is
a virtual platform.

=A0"mpc85xx-hv"
=A0"corenet-32-hv"
=A0"corenet-64-hv"

However, compatible values are cheap and while theoretically any
hypervisor could create a similar machine, the reality is probably
subtle difference between the implementations.  I'd rather see the
compatible reflect the specific implementation.

g.