Author: jhb
Date: Wed Sep 10 21:25:54 2014
New Revision: 271408
URL: http://svnweb.freebsd.org/changeset/base/271408
Log:
To workaround an errata on certain Pentium Pro CPUs, i386 disables
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.
Modified:
head/sys/i386/i386/initcpu.c
head/sys/i386/include/md_var.h
head/sys/x86/x86/local_apic.c
Modified: head/sys/i386/i386/initcpu.c
==============================================================================
--- head/sys/i386/i386/initcpu.c Wed Sep 10 21:24:15 2014
(r271407)
+++ head/sys/i386/i386/initcpu.c Wed Sep 10 21:25:54 2014
(r271408)
@@ -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;
+ }
}
/*
Modified: head/sys/i386/include/md_var.h
==============================================================================
--- head/sys/i386/include/md_var.h Wed Sep 10 21:24:15 2014
(r271407)
+++ head/sys/i386/include/md_var.h Wed Sep 10 21:25:54 2014
(r271408)
@@ -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);
Modified: head/sys/x86/x86/local_apic.c
==============================================================================
--- head/sys/x86/x86/local_apic.c Wed Sep 10 21:24:15 2014
(r271407)
+++ head/sys/x86/x86/local_apic.c Wed Sep 10 21:25:54 2014
(r271408)
@@ -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. */
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