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SubjectRe: [PATCH] i386/bigsmp: eliminate false warnings regarding logical APIC ID mismatches
>>> On 27.09.11 at 15:35, Ingo Molnar <mingo@elte.hu> wrote:

> * Jan Beulich <JBeulich@novell.com> wrote:
>
>> These warnings (generally one per CPU) are a result of initializing
>> x86_cpu_to_logical_apicid while apic_default is still in use, but the
>> check in setup_local_APIC() being done when apic_bigsmp was already
>> used as an override in default_setup_apic_routing():
>>
>> Overriding APIC driver with bigsmp
>> Enabling APIC mode: Physflat. Using 5 I/O APICs
>> ------------[ cut here ]------------
>> WARNING: at .../arch/x86/kernel/apic/apic.c:1239
> setup_local_APIC+0x137/0x46b()
>> Hardware name: ...
>> CPU0 logical APIC ID: 1 != 0
>> Pid: 1, comm: swapper Not tainted 3.0.1-2011-08-09-jb #2
>> Call Trace:
>> [<c1005f91>] try_stack_unwind+0x1b1/0x1f0
>> [<c1004cc7>] dump_trace+0x47/0x110
>> [<c1005b0b>] show_trace_log_lvl+0x4b/0x60
>> [<c1005b38>] show_trace+0x18/0x20
>> [<c1261435>] dump_stack+0x6d/0x72
>> [<c10355f7>] warn_slowpath_common+0x77/0xb0
>> [<c10356c3>] warn_slowpath_fmt+0x33/0x40
>> [<c13fda81>] setup_local_APIC+0x137/0x46b
>> [<c13d1733>] native_smp_prepare_cpus+0x108/0x1cd
>> [<c13c61ff>] kernel_init+0x37/0x12c
>> [<c1264826>] kernel_thread_helper+0x6/0xd
>> ---[ end trace 4eaa2a86a8e2da22 ]---
>> ...
>> CPU 1 irqstacks, hard=f1c9a000 soft=f1c9c000
>> Booting Node 0, Processors #1
>> smpboot cpu 1: start_ip = 9e000
>> Initializing CPU#1
>> ------------[ cut here ]------------
>> WARNING: at .../arch/x86/kernel/apic/apic.c:1239
> setup_local_APIC+0x137/0x46b()
>> Hardware name: ...
>> CPU1 logical APIC ID: 2 != 8
>> ...
>>
>> Fix this (for the time being, i.e. until x86_32_early_logical_apicid()
>> will get removed again, as Tehun says ought to be possible) by
>> overriding the previously stored values at the point where the APIC
>> driver gets overridden.
>>
>> Signed-off-by: Jan Beulich <jbeulich@novell.com>
>> Cc: Tejun Heo <tj@kernel.org>
>> Cc: stable@kernel.org (2.6.39 and onwards)
>>
>> ---
>> arch/x86/kernel/apic/probe_32.c | 11 +++++++++++
>> 1 file changed, 11 insertions(+)
>>
>> --- 3.1-rc2/arch/x86/kernel/apic/probe_32.c
>> +++ 3.1-rc2-i386-bigsmp-early-lapicid-override/arch/x86/kernel/apic/probe_32.c
>> @@ -203,7 +203,18 @@ void __init default_setup_apic_routing(v
>> if (!cmdline_apic && apic == &apic_default) {
>> struct apic *bigsmp = generic_bigsmp_probe();
>> if (bigsmp) {
>> + unsigned int cpu;
>> +
>> apic = bigsmp;
>> + for_each_possible_cpu(cpu) {
>> + if (early_per_cpu(x86_cpu_to_logical_apicid,
>> + cpu) == BAD_APICID)
>> + continue;
>> + early_per_cpu(x86_cpu_to_logical_apicid,
>> + cpu) =
>> + bigsmp->x86_32_early_logical_apicid
>> + (cpu);
>> + }
>> printk(KERN_INFO "Overriding APIC driver with %s\n",
>> apic->name);
>> }
>
> This could move into a separate function i suspect, which would
> de-uglify it quite significantly?

If that's the only concern, then sure - I'll re-submit with this broken out.

Jan



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