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Don't check the CPUID_APIC bit in the cpu_features flags field to determine

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if the boot CPU has a local APIC because some BIOS vendors are not
competent enough to set this bit.  Instead, just assume that we always have
a local APIC on amd64.  For i386 the check is a bit more subtle.  FreeBSD
requires either an MP Table or an ACPI MADT table to enumerate APICs.  The
only systems that have one of those tables that don't have local APICs are
some presumably rare (and old) SMP 486 systems using external APICs.  Thus,
instead of checking the CPUID_APIC flag, check the CPU class and abort if
we are running on a 486.

MFC after:	1 week
Reported by:	bz
This commit is contained in:
John Baldwin 2005-12-13 15:09:40 +00:00
parent 412295fdbd
commit 15b7edbeaa
2 changed files with 9 additions and 6 deletions
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4
sys/amd64/amd64/local_apic.c
View File

@ -831,10 +831,6 @@ apic_init(void *dummy __unused)
struct apic_enumerator *enumerator;
int retval, best;
/* We only support built in local APICs. */
if (!(cpu_feature & CPUID_APIC))
return;
/* Don't probe if APIC mode is disabled. */
if (resource_disabled("apic", 0))
return;

11
sys/i386/i386/local_apic.c
View File

@ -834,8 +834,15 @@ apic_init(void *dummy __unused)
uint64_t apic_base;
int retval, best;
/* We only support built in local APICs. */
if (!(cpu_feature & CPUID_APIC))
/*
* We only support built in local APICs. Unfortunately, we can't
* just check the CPUID_APIC bit in cpu_features because some BIOSen
* don't set that flag. Instead, we assume that all Pentium-class
* and later machines have a local APIC. The only non-Pentium-class
* CPUs that can talk to an external APIC are 486s, so we just
* bail if we are on a 486.
*/
if (cpu_class == CPUCLASS_486)
return;
/* Don't probe if APIC mode is disabled. */