Re: [PATCH] x86: add /proc/cpuinfo/physical id quirks

* Suresh Siddha <suresh.b.siddha@xxxxxxxxx>:
On Wed, 2009-08-19 at 14:02 -0700, Alex Chiang wrote:
I agree with you (although I thought that they should be
0-based) but this quirk addresses a specific platform, where
I can assume certain things about the BIOS, etc.

What happens if for some reason, newer bios/newer cpu
generations on this platform start having holes in the physical
id space? We can't rule out these kind of changes and we don't
want to go behind distros requesting fixes.

I agree with you in general, but again, this is a specific
platform quirk where I have a good idea of what is a
supported configuration.

I am just nervous about future bios changes etc.

Ok, let's separate the two conversations happening here.

To me, the BIOS concerns are moot. I work closely with the BIOS
engineers for this platform; I have knowledge of future plans for
this BIOS and platform; and I know that they will not make any
changes that break the assumptions in my patch.

If they do, we will catch it during platform testing, file a bug,
and not let them release their BIOS until it's fixed. Does that
satisfy you? :)

So the algorithm for mapping an APIC ID to a physical/chassis ID
for this platform will not ever change.

Now on the other hand, the /interface/ that we present to the
user is the interesting conversation to have.

Easiest route will be to add a new entry in /proc/cpuinfo

Well, if you remain unconvinced that fixing up 'physical id' is
the proper thing to do, here are some alternate proposals:

/proc/cpuinfo/chassis id
/sys/devices/system/cpu/$cpu/chassis id
/sys/devices/system/cpu/$cpu/topology/chassis id


I really like this alternate proposal. This is simple and straight
forward to everyone.

I am leaning towards sysfs, and prefer:

/sys/devices/system/cpu/$cpu/chassis_id

How does that sound?

Thanks.

/ac

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