[LinuxBIOS] [PATCH] AMD Barcelona(family 10) support 4 of 4 - coreboot

13 Dec 2007

Changes to core lapic.h. This file is used by Intel multiprocessor CPUs 
  as well as AMDs. Could someone with Intel APIC experience take a close 
look at this and try it?
Marc
-- 
Marc Jones
Senior Firmware Engineer
(970) 226-9684 Office
mailto:Marc.Jones@amd.com
http://www.amd.com/embeddedprocessors

Changed the stop_this_cpu() to just hlt.
Removed local APIC INIT (don't worry the APIC and AP are still initialized).

The local APIC INIT seemed to be the incorrect thing to do to stop an AP.
The Intel Multiprocessor specification indicated that a vector should be set
and a START should happen following an INIT. Then AP will execute the 
instructions pointed to by the vector. There is no vector or start in
stop_this_cpu(). This seems to put the AP in an in-between state. In the case
of Barcelona the AP's MSRs and PCI register are not accessible by the hardware
debugger.

The better solution seems to be to just put the AP in a hlt and allow the AP
to go into C1. Then APIC managing software running on the BSP can program the
AP as needed.

Signed-off-by: Marc Jones marc.jones@amd.com
Reviewed-by: Jordan Crouse jordan.crouse@amd.com

Index: LinuxBIOSv2/src/include/cpu/x86/lapic.h
===================================================================

--- LinuxBIOSv2.orig/src/include/cpu/x86/lapic.h	2007-12-12 11:59:13.000000000 -0700
+++ LinuxBIOSv2/src/include/cpu/x86/lapic.h	2007-12-12 14:30:03.000000000 -0700
@@ -54,22 +54,7 @@
 static inline __attribute__((always_inline)) void stop_this_cpu(void)
 {

-	unsigned apicid;
-	apicid = lapicid();
-
-	/* Send an APIC INIT to myself */
-	lapic_write(LAPIC_ICR2, SET_LAPIC_DEST_FIELD(apicid));
-	lapic_write(LAPIC_ICR, LAPIC_INT_LEVELTRIG | LAPIC_INT_ASSERT | LAPIC_DM_INIT);
-	/* Wait for the ipi send to finish */
-	lapic_wait_icr_idle();
-
-	/* Deassert the APIC INIT */
-	lapic_write(LAPIC_ICR2, SET_LAPIC_DEST_FIELD(apicid));
-	lapic_write(LAPIC_ICR,  LAPIC_INT_LEVELTRIG | LAPIC_DM_INIT);
-	/* Wait for the ipi send to finish */
-	lapic_wait_icr_idle();
-
-	/* If I haven't halted spin forever */
+	/* Called by an AP when it is ready to halt and wait for a new task */
    for(;;) {
    	hlt();
    }

    