From 7b37b5fd9ba32c0c5afc3537eed7e7466f2173e2 Mon Sep 17 00:00:00 2001 From: Len Brown Date: Tue, 23 Dec 2008 01:47:42 -0500 Subject: [PATCH] ACPI: disable MPS when NO APIC-table found When ACPI is asked to find an MADT (APIC table) and fails, then ACPI expects to run in PIC mode. However, if an MP Table is was found, IRQs will be registered as if an IOAPIC is being used, even though ACPI is configuring interrupt links links for PIC mode. In this scenario, disable MPS so that IRQs are registered in PIC mode, consistent with ACPI. http://bugzilla.kernel.org/show_bug.cgi?id=12257 Signed-off-by: Len Brown --- arch/x86/kernel/acpi/boot.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c index 4c51a2f8fd31..de8ce79dd881 100644 --- a/arch/x86/kernel/acpi/boot.c +++ b/arch/x86/kernel/acpi/boot.c @@ -1359,6 +1359,17 @@ static void __init acpi_process_madt(void) "Invalid BIOS MADT, disabling ACPI\n"); disable_acpi(); } + } else { + /* + * ACPI found no MADT, and so ACPI wants UP PIC mode. + * In the event an MPS table was found, forget it. + * 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; + } } #endif return; -- 2.34.1