Messages in this thread | | | Date | Tue, 25 Aug 2009 11:35:03 -0700 | From | Yinghai Lu <> | Subject | Re: [patch] x86: 2.6.31-rc7 crash due to buggy flat_phys_pkg_id |
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Ingo Molnar wrote: > * Ravikiran G Thirumalai <kiran@scalex86.org> wrote: > >> On Mon, Aug 24, 2009 at 10:12:01PM -0700, Yinghai Lu wrote: >>> Ravikiran G Thirumalai wrote: >>>> On Mon, Aug 24, 2009 at 04:53:45PM -0700, Yinghai Lu wrote: >>>>> Ravikiran G Thirumalai wrote: >>>>>> Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org> >>>>>> Cc: Yinghai Lu <yinghai@kernel.org> >>>>>> >>>> Why? The specs seem to indicate otherwise unless I am mistaken -- >>>> Intel systems programming guide, Vol 3A Part1, chapter 7 section >>>> 7.5.5 - Identifying Logical Processors in a MP system: >>>> <quote> >>>> After the BIOS has completed the MP initialization protocol, each logical >>>> processor can be uniquely identified by its local APIC ID. Software can >>>> access these APIC IDs in either of the following ways >>>> </quote> >>>> phys_pkg_id() indicates that the logical package id is being looked up, >>>> so local apic id should be used here no? >>>> What am I missing? >>> initial apic id : it can not changed, there is fixed mapping from that to physical processor id aka socket id / node id. >>> >>> apic id: could be changed by BIOS to any value. there is no good way to get phys_pkg_id from that. >>> >> But BIOS is supposed to change it to a sane value. Until 2.6.30, >> local apic id has been used to get phys_pkg_id for the 'flat' >> apics! What changed? Was this changed for a BIOS bug? Even the >> intel books seem to indicate local apic usage! > > We should revert to the .30 behavior unless there's a good reason > (even in that case we'll solve the regression and do a workaround > for vSMP). Yinghai?
we should stop overloading phys_pkg_id to get physical processor id (socket id ?) and apic id.
we need to find out what vSMP initial apic id looks like. and have one better phys_pkg_id for it.
otherwise we have problem with intel system that have apic id changing by BIOS too.
YH
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