From: Kevin O'Connor <kevin@koconnor.net>
Date: Thu, 11 Mar 2010 03:32:26 +0000 (-0500)
Subject: Fix smp cpu detect on gcc 4.5.
X-Git-Tag: rel-0.6.0~17
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=808939c17f603f3c7ad5abfb882cee55f636867b;p=seabios.git

Fix smp cpu detect on gcc 4.5.

Bruce Rogers <brogers@novell.com> observed new compiler optimizing
away memory assign in smp detect.  Add barrier() to code to ensure gcc
knows the SIPI can read/write memory.
---

diff --git a/src/smp.c b/src/smp.c
index dac95bf..f989ec1 100644
--- a/src/smp.c
+++ b/src/smp.c
@@ -103,6 +103,7 @@ smp_probe(void)
     }
 
     // broadcast SIPI
+    barrier();
     writel(APIC_ICR_LOW, 0x000C4500);
     u32 sipi_vector = BUILD_AP_BOOT_ADDR >> 12;
     writel(APIC_ICR_LOW, 0x000C4600 | sipi_vector);
@@ -113,7 +114,7 @@ smp_probe(void)
     } else {
         u8 cmos_smp_count = inb_cmos(CMOS_BIOS_SMP_COUNT);
         while (cmos_smp_count + 1 != readl(&CountCPUs))
-             ;
+            yield();
     }
 
     // Restore memory.