Messages in this thread | | | Date | Tue, 25 Aug 2009 10:17:16 -0700 | From | Ravikiran G Thirumalai <> | Subject | Re: [patch] x86: 2.6.31-rc7 crash due to buggy flat_phys_pkg_id |
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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!
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