On Wed, 2006-01-25 at 09:07 +0100, Arjan van de Ven wrote:
> On Tue, 2006-01-24 at 23:59 -0800, Andrew Morton wrote:
> > Andi Kleen <[email protected]> wrote:
> > >
> > > On Wednesday 25 January 2006 08:10, Andrew Morton wrote:
> > >
> > > > It assumes that all x86 SMP machines have APICs. That's untrue of Voyager.
> > > > I think we can probably live with this assumption - others would know
> > > > better than I.
> > >
> > > Early x86s didn't have APICs and they are still often disabled on not so
> > > old mobile CPUs. I don't think it's a good assumption to make for i386.
> > >
> >
> > But how many of those do SMP?
>
> even on SMP boxes you regularly need to (runtime) disable apics. Several
> boards out there just have busted apics, or at least when used with
> linux. "noapic" is one of the more frequent things distro support people
> tell customers over the phone....
Checking whether ioapic_setup_disabled is set should suffice, right?
Does the patch below look good?
diff -urNp linux-2.6.16-rc1/arch/i386/kernel/smp.c linux-2.6.16-rc1-sov/arch/i386/kernel/smp.c
--- linux-2.6.16-rc1/arch/i386/kernel/smp.c 2006-01-03 12:21:10.000000000 +0900
+++ linux-2.6.16-rc1-sov/arch/i386/kernel/smp.c 2006-01-25 17:49:52.000000000 +0900
@@ -628,3 +628,32 @@ fastcall void smp_call_function_interrup
}
}
+static int convert_apicid_to_cpu(int apic_id)
+{
+ int i;
+
+ for (i = 0; i < NR_CPUS; i++) {
+ if (x86_cpu_to_apicid[i] == apic_id)
+ return i;
+ }
+ return -1;
+}
+
+int safe_smp_processor_id(void)
+{
+ int apicid, cpuid;
+
+ if (ioapic_setup_disabled())
+ return smp_processor_id();
+
+ if (!boot_cpu_has(X86_FEATURE_APIC))
+ return 0;
+
+ apicid = hard_smp_processor_id();
+ if (apicid == BAD_APICID)
+ return 0;
+
+ cpuid = convert_apicid_to_cpu(apicid);
+
+ return cpuid >= 0 ? cpuid : 0;
+}
diff -urNp linux-2.6.16-rc1/include/asm-i386/smp.h linux-2.6.16-rc1-sov/include/asm-i386/smp.h
--- linux-2.6.16-rc1/include/asm-i386/smp.h 2006-01-03 12:21:10.000000000 +0900
+++ linux-2.6.16-rc1-sov/include/asm-i386/smp.h 2006-01-25 18:00:04.000000000 +0900
@@ -90,12 +90,14 @@ static __inline int logical_smp_processo
#endif
+extern int safe_smp_processor_id(void);
extern int __cpu_disable(void);
extern void __cpu_die(unsigned int cpu);
#endif /* !__ASSEMBLY__ */
#else /* CONFIG_SMP */
+#define safe_smp_processor_id() 0
#define cpu_physical_id(cpu) boot_cpu_physical_apicid
#define NO_PROC_ID 0xFF /* No processor magic marker */
-
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