[PATCH] fix APIC errors on oprofile restore

John Levon (levon@movementarian.org)
Fri, 1 Nov 2002 04:07:29 +0000


See comment. Please apply. By Philippe Elie

tested on two UP boxen and my SMP box

thanks
john

diff -Naur -X dontdiff linux-linus/arch/i386/oprofile/nmi_int.c linux/arch/i386/oprofile/nmi_int.c
--- linux-linus/arch/i386/oprofile/nmi_int.c Wed Oct 30 03:28:21 2002
+++ linux/arch/i386/oprofile/nmi_int.c Wed Oct 30 03:51:58 2002
@@ -135,9 +135,19 @@

static void nmi_cpu_shutdown(void * dummy)
{
+ unsigned int v;
int cpu = smp_processor_id();
struct op_msrs * msrs = &cpu_msrs[cpu];
+
+ /* restoring APIC_LVTPC can trigger an apic error because the delivery
+ * mode and vector nr combination can be illegal. That's by design: on
+ * power on apic lvt contain a zero vector nr which are legal only for
+ * NMI delivery mode. So inhibit apic err before restoring lvtpc
+ */
+ v = apic_read(APIC_LVTERR);
+ apic_write(APIC_LVTERR, v | APIC_LVT_MASKED);
apic_write(APIC_LVTPC, saved_lvtpc[cpu]);
+ apic_write(APIC_LVTERR, v);
nmi_restore_registers(msrs);
}

-
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