Messages in this thread | | | Date | Fri, 14 Aug 2009 13:27:30 -0600 | From | Alex Chiang <> | Subject | Re: [PATCH] x86: add /proc/cpuinfo/physical id quirks |
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* Suresh Siddha <suresh.b.siddha@intel.com>: > On Fri, 2009-08-14 at 09:36 -0700, Alex Chiang wrote: > > As systems become larger and more complex, it is not always possible > > to assume that an APIC ID maps directly to a given physical slot. > > > > From a UI point-of-view, it's nice if the 'physical id' field in > > /proc/cpuinfo matches the silk-screening or labelling on the system > > chassis. > > > > Add a quirk that allows oddball platforms to ensure that what the kernel > > displays in /proc/cpuinfo matches the physical reality. > > Alex, Does it makes sense to add a new entry in /proc/cpuinfo rather > than overloading the 'physical id' by modifying phys_proc_id.
Hm, I'm not entirely sure about that, for two reasons.
First (and this is the weaker reason), I'd prefer not to keep adding new fields to /proc/cpuinfo if we can help it, as it just makes for a continually more complicated ABI/API for userspace.
Second, I guess I'm not sure what else 'physical id' /should/ represent. I'm willing to be corrected on this point, so if I'm wrong, just call it simple ignorance. :)
> That way, even if there is a mis-match between the bios and the > OS fixup tables, we won't screw up other topology setup etc in > the kernel that are dependent on the phys_proc_id.
My quick grep earlier led me to believe that as long as the phys_proc_ids were /consistent/ then it didn't seem to matter what their /values/ were.
In other words, my patch simply says, "all cores that had phys_proc_id X now have phys_proc_id Y". All the cores on a physical package have identical phys_proc_ids, and cores on a different physical package do /not/ collide.
But again, that just might be my ignorance again. If we do indeed care about the values of phys_proc_ids, please let me know and I'd be happy to rework the patch.
Thanks.
/ac
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