ACPI : Use RSDT instead of XSDT by adding boot option of "acpi=rsdt"

On some boxes there exist both RSDT and XSDT table. But unfortunately
sometimes there exists the following error when XSDT table is used:
   a. 32/64X address mismatch
   b. The 32/64X FACS address mismatch

   In such case the boot option of "acpi=rsdt" is provided so that
RSDT is tried instead of XSDT table when the system can't work well.

http://bugzilla.kernel.org/show_bug.cgi?id=8246

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
cc:Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 6 insertions, 1 deletions

diff --git a/arch/ia64/kernel/acpi.c b/arch/ia64/kernel/acpi.c
index bd7acc71e8a9..c19b686db9b8 100644
--- a/arch/ia64/kernel/acpi.c
+++ b/arch/ia64/kernel/acpi.c
@@ -65,6 +65,7 @@ EXPORT_SYMBOL(pm_idle);
 void (*pm_power_off) (void);
 EXPORT_SYMBOL(pm_power_off);
 
+u32 acpi_rsdt_forced;
 unsigned int acpi_cpei_override;
 unsigned int acpi_cpei_phys_cpuid;
 
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 4c51a2f8fd31..db1a90a76b3e 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -47,7 +47,7 @@
 #endif
 
 static int __initdata acpi_force = 0;
-
+u32 acpi_rsdt_forced;
 #ifdef  CONFIG_ACPI
 int acpi_disabled = 0;
 #else
@@ -1783,6 +1783,10 @@ static int __init parse_acpi(char *arg)
                         disable_acpi();
                 acpi_ht = 1;
         }
+        /* acpi=rsdt use RSDT instead of XSDT */
+        else if (strcmp(arg, "rsdt") == 0) {
+                acpi_rsdt_forced = 1;
+        }
         /* "acpi=noirq" disables ACPI interrupt routing */
         else if (strcmp(arg, "noirq") == 0) {
                 acpi_noirq_set();