From: Stoney Wang Subject: [PATCH] x86, apic: Check fadt x2apic phys in x2apic_phys_probe() HP has systems that work with x2apic phys mode and BIOS set ACPI_FADT_APIC_PHYSICAL in FADT table, and all cpuid < 255, the spec requires BIOS only put system on xapic mode. Kernel will set to x2apic logical mode instead of x2apic phys mode. Current code handle x2apic as: 1. BIOS set x2apic mode: When user specify x2apic_phys, or FADT indicates PHYSICAL. During madt oem check, apic driver will set correctly to x2apic phys driver. 2. BIOS does NOT set x2apic mode: When user specify x2apic_phys, or FADT indicates PHYSICAL. During madt oem check, apic driver will get set with xapic logical or xapic phys driver at first. Later enable_IR_x2apic() will enable x2apic_mode. After that, x2apic_phys_probe() get called. That will install right x2apic physical driver when user specify x2apic_phys, but will install wrong apic driver (x2apic logical) when FADT indicates PHYSICAL, because that probe does not check FADT PHYSICAL. Fix that by adding check x2apic_fadt_phys in x2apic_phys_probe(). [ changelog, and simplify code - Yinghai Lu ] Signed-off-by: Stoney Wang Signed-off-by: Yinghai Lu --- arch/x86/kernel/apic/x2apic_phys.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) Index: linux-2.6/arch/x86/kernel/apic/x2apic_phys.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/apic/x2apic_phys.c +++ linux-2.6/arch/x86/kernel/apic/x2apic_phys.c @@ -20,18 +20,19 @@ static int set_x2apic_phys_mode(char *ar } early_param("x2apic_phys", set_x2apic_phys_mode); -static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id) +static int x2apic_fadt_phys(void) { - if (x2apic_phys) - return x2apic_enabled(); - else if ((acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID) && - (acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL) && - x2apic_enabled()) { + if ((acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID) && + (acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL)) { printk(KERN_DEBUG "System requires x2apic physical mode\n"); return 1; } - else - return 0; + return 0; +} + +static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id) +{ + return x2apic_enabled() && (x2apic_phys || x2apic_fadt_phys()); } static void @@ -82,7 +83,7 @@ static void init_x2apic_ldr(void) static int x2apic_phys_probe(void) { - if (x2apic_mode && x2apic_phys) + if (x2apic_mode && (x2apic_phys || x2apic_fadt_phys())) return 1; return apic == &apic_x2apic_phys;