PATCH: Allow over-ride of smp_found_cfg with kernel cmd-line option.

[Ben Greear <greearb@candelatech.com>]

[-- Attachment #1: Type: text/plain, Size: 471 bytes --]

Allow user to keep smp_found_cfg set to 1 even if MADT
cannot be parsed.  This works around funky BIOS on FWA-7304
(VIA CN700 chipset) system, and possibly other systems as well.
Without this override, performance drops by around 15% on
network throughput tests on this system.

This is based on 2.6.29-rc3

Signed-Off-By:  Ben Greear <greearb@candelatech.com>


Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com


[-- Attachment #2: patch1.patch --]
[-- Type: text/x-patch, Size: 1395 bytes --]

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index d37593c..e96bf19 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -87,6 +87,7 @@ u8 acpi_sci_flags __initdata;
 int acpi_sci_override_gsi __initdata;
 int acpi_skip_timer_override __initdata;
 int acpi_use_timer_override __initdata;
+int force_smp_found_cfg __initdata;
 
 #ifdef CONFIG_X86_LOCAL_APIC
 static u64 acpi_lapic_addr __initdata = APIC_DEFAULT_PHYS_BASE;
@@ -1335,6 +1336,14 @@ static void __init early_acpi_process_madt(void)
 #endif
 }
 
+static int __init parse_force_smp_found_cfg(char *arg)
+{
+	force_smp_found_cfg = 1;
+	return 0;
+}
+early_param("force_smp_found_cfg", parse_force_smp_found_cfg);
+
+
 static void __init acpi_process_madt(void)
 {
 #ifdef CONFIG_X86_LOCAL_APIC
@@ -1381,9 +1390,14 @@ static void __init acpi_process_madt(void)
  		 * Boot with "acpi=off" to use MPS on such a system.
  		 */
 		if (smp_found_config) {
-			printk(KERN_WARNING PREFIX
-				"No APIC-table, disabling MPS\n");
-			smp_found_config = 0;
+			if (force_smp_found_cfg)
+				printk(KERN_WARNING PREFIX
+				       "No APIC-table, wanted to disable MPS, but will not\n  due to force_smp_found_cfg=1\n");
+			else {
+				printk(KERN_WARNING PREFIX
+				       "No APIC-table, disabling MPS.  Use force_smp_found_cfg=1 to override\n");
+				smp_found_config = 0;
+			}
 		}
 	}