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    SubjectRe: [tip:x86/urgent] x86: Detect use of extended APIC ID for AMD CPUs
    tip-bot for Andreas Herrmann wrote:
    > Commit-ID: 37f36c1017f0032fa7a1fb85a0cddfc0d526d17f
    > Gitweb: http://git.kernel.org/tip/37f36c1017f0032fa7a1fb85a0cddfc0d526d17f
    > Author: Andreas Herrmann <andreas.herrmann3@amd.com>
    > AuthorDate: Thu, 4 Jun 2009 12:40:16 +0200
    > Committer: Ingo Molnar <mingo@elte.hu>
    > CommitDate: Sun, 7 Jun 2009 16:39:38 +0200
    >
    > x86: Detect use of extended APIC ID for AMD CPUs
    >
    > Booting a 32-bit kernel on Magny-Cours results in the following panic
    >
    > ...
    > Using APIC driver default
    > ...
    > Overriding APIC driver with bigsmp
    > ...
    > Getting VERSION: 80050010
    > Getting VERSION: 80050010
    > Getting ID: 10000000
    > Getting ID: ef000000
    > Getting LVT0: 700
    > Getting LVT1: 10000
    > Kernel panic - not syncing: Boot APIC ID in local APIC unexpected (16 vs 0)
    > Pid: 1, comm: swapper Not tainted 2.6.30-rcX #2
    > Call Trace:
    > [<c05194da>] ? panic+0x38/0xd3
    > [<c0743102>] ? native_smp_prepare_cpus+0x259/0x31f
    > [<c073b19d>] ? kernel_init+0x3e/0x141
    > [<c073b15f>] ? kernel_init+0x0/0x141
    > [<c020325f>] ? kernel_thread_helper+0x7/0x10
    >
    > The reason is that default_get_apic_id handled extension of local APIC
    > ID field just in case of XAPIC.
    >
    > Thus for this AMD CPU, default_get_apic_id() returns 0 and
    > bigsmp_get_apic_id() returns 16 which leads to the respective kernel
    > panic.
    >
    > This patch introduces a Linux specific feature flag to indicate
    > support for extended APIC id (8 bits instead of 4 bits width) and sets
    > the flag on AMD CPUs if applicable.
    >
    > Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
    > Cc: <stable@kernel.org>
    > LKML-Reference: <20090604104016.GT5736@alberich.amd.com>
    > Signed-off-by: Ingo Molnar <mingo@elte.hu>
    >
    >
    > ---
    > arch/x86/include/asm/apic.h | 2 +-
    > arch/x86/include/asm/cpufeature.h | 1 +
    > arch/x86/kernel/cpu/amd.c | 10 ++++++++++
    > 3 files changed, 12 insertions(+), 1 deletions(-)
    >
    > diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
    > index 42f2f83..9b2c049 100644
    > --- a/arch/x86/include/asm/apic.h
    > +++ b/arch/x86/include/asm/apic.h
    > @@ -410,7 +410,7 @@ static inline unsigned default_get_apic_id(unsigned long x)
    > {
    > unsigned int ver = GET_APIC_VERSION(apic_read(APIC_LVR));
    >
    > - if (APIC_XAPIC(ver))
    > + if (APIC_XAPIC(ver) || boot_cpu_has(X86_FEATURE_EXTD_APICID))
    > return (x >> 24) & 0xFF;
    > else
    > return (x >> 24) & 0x0F;

    looks like we should fix APIC_XAPIC() or have one global apic_ver.

    YH


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