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To workaround an errata on certain Pentium Pro CPUs, i386 disables

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the local APIC in initializecpu() and re-enables it if the APIC code
decides to use the local APIC after all.  Rework this workaround
slightly so that initializecpu() won't re-disable the local APIC if
it is called after the APIC code re-enables the local APIC.
This commit is contained in:
John Baldwin 2014-09-10 21:25:54 +00:00
parent a005d36245
commit 645b112b68
3 changed files with 27 additions and 13 deletions
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28
sys/i386/i386/initcpu.c
View File

@ -533,6 +533,8 @@ init_6x86MX(void)
intr_restore(saveintr);
}
static int ppro_apic_used = -1;
static void
init_ppro(void)
{
@ -541,9 +543,29 @@ init_ppro(void)
/*
* Local APIC should be disabled if it is not going to be used.
*/
apicbase = rdmsr(MSR_APICBASE);
apicbase &= ~APICBASE_ENABLED;
wrmsr(MSR_APICBASE, apicbase);
if (ppro_apic_used != 1) {
apicbase = rdmsr(MSR_APICBASE);
apicbase &= ~APICBASE_ENABLED;
wrmsr(MSR_APICBASE, apicbase);
ppro_apic_used = 0;
}
}
/*
* If the local APIC is going to be used after being disabled above,
* re-enable it and don't disable it in the future.
*/
void
ppro_reenable_apic(void)
{
u_int64_t apicbase;
if (ppro_apic_used == 0) {
apicbase = rdmsr(MSR_APICBASE);
apicbase |= APICBASE_ENABLED;
wrmsr(MSR_APICBASE, apicbase);
ppro_apic_used = 1;
}
}
/*

1
sys/i386/include/md_var.h
View File

@ -109,6 +109,7 @@ int is_physical_memory(vm_paddr_t addr);
int isa_nmi(int cd);
vm_paddr_t kvtop(void *addr);
void panicifcpuunsupported(void);
void ppro_reenable_apic(void);
void printcpuinfo(void);
void setidt(int idx, alias_for_inthand_t *func, int typ, int dpl, int selec);
int user_dbreg_trap(void);

11
sys/x86/x86/local_apic.c
View File

@ -55,7 +55,6 @@ __FBSDID("$FreeBSD$");
#include <vm/pmap.h>
#include <x86/apicreg.h>
#include <machine/cpu.h>
#include <machine/cputypes.h>
#include <machine/frame.h>
#include <machine/intr_machdep.h>
@ -1331,9 +1330,6 @@ static void
apic_init(void *dummy __unused)
{
struct apic_enumerator *enumerator;
#ifndef __amd64__
uint64_t apic_base;
#endif
int retval, best;
/* We only support built in local APICs. */
@ -1375,12 +1371,7 @@ apic_init(void *dummy __unused)
* CPUs during early startup. We need to turn the local APIC back
* on on such CPUs now.
*/
if (cpu == CPU_686 && cpu_vendor_id == CPU_VENDOR_INTEL &&
(cpu_id & 0xff0) == 0x610) {
apic_base = rdmsr(MSR_APICBASE);
apic_base |= APICBASE_ENABLED;
wrmsr(MSR_APICBASE, apic_base);
}
ppro_reenable_apic();
#endif
/* Probe the CPU's in the system. */