From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Fix up the 8259 ack handling for buggy SMM firmware.
See http://www.ussg.iu.edu/hypermail/linux/kernel/0203.2/0956.html
Apparently the embedded 8259A-compatible core is not fully functional.
This patch lets the I/O APIC-driven NMI watchdog to function correctly.
Credit to Ross Dickson for discovering this.
---
arch/i386/kernel/io_apic.c | 20 ++++++++++++++++----
1 files changed, 16 insertions(+), 4 deletions(-)
diff -puN arch/i386/kernel/io_apic.c~8259-timer-ack-fix arch/i386/kernel/io_apic.c
--- 25/arch/i386/kernel/io_apic.c~8259-timer-ack-fix 2004-02-06 18:03:45.000000000 -0800
+++ 25-akpm/arch/i386/kernel/io_apic.c 2004-02-06 18:06:00.000000000 -0800
@@ -2155,6 +2155,10 @@ static inline void check_timer(void)
{
int pin1, pin2;
int vector;
+ unsigned int ver;
+
+ ver = apic_read(APIC_LVR);
+ ver = GET_APIC_VERSION(ver);
/*
* get/set the timer IRQ vector:
@@ -2168,11 +2172,17 @@ static inline void check_timer(void)
* mode for the 8259A whenever interrupts are routed
* through I/O APICs. Also IRQ0 has to be enabled in
* the 8259A which implies the virtual wire has to be
- * disabled in the local APIC.
+ * disabled in the local APIC. Finally timer interrupts
+ * need to be acknowledged manually in the 8259A for
+ * do_slow_timeoffset() and for the i82489DX when using
+ * the NMI watchdog.
*/
apic_write_around(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT);
init_8259A(1);
- timer_ack = 1;
+ if (nmi_watchdog == NMI_IO_APIC && !APIC_INTEGRATED(ver))
+ timer_ack = 1;
+ else
+ timer_ack = !cpu_has_tsc;
enable_8259A_irq(0);
pin1 = find_isa_irq_pin(0, mp_INT);
@@ -2190,7 +2200,8 @@ static inline void check_timer(void)
disable_8259A_irq(0);
setup_nmi();
enable_8259A_irq(0);
- check_nmi_watchdog();
+ if (check_nmi_watchdog() < 0);
+ timer_ack = !cpu_has_tsc;
}
return;
}
@@ -2213,7 +2224,8 @@ static inline void check_timer(void)
add_pin_to_irq(0, 0, pin2);
if (nmi_watchdog == NMI_IO_APIC) {
setup_nmi();
- check_nmi_watchdog();
+ if (check_nmi_watchdog() < 0);
+ timer_ack = !cpu_has_tsc;
}
return;
}
_