From: Suresh Siddha Subject: x64, x2apic/intr-remap: Interrupt-remapping and x2apic support, fix References: fate #303948 and fate #303984 Patch-Mainline: queued for .28 Commit-ID: 2d7a66d02e11af9ab8e16c76d22767e622b4e3d7 Signed-off-by: Thomas Renninger Yinghai Lu wrote: > Setting APIC routing to physical flat > Kernel panic - not syncing: Boot APIC ID in local APIC unexpected (0 vs 4) > Pid: 1, comm: swapper Not tainted 2.6.26-rc9-tip-01763-g74f94b1-dirty #320 > > Call Trace: > [] ? set_cpu_sibling_map+0x38c/0x3bd > [] ? read_xapic_id+0x25/0x3e > [] ? verify_local_APIC+0x139/0x1b9 > [] ? read_xapic_id+0x25/0x3e > [] ? native_smp_prepare_cpus+0x224/0x2e9 > [] ? kernel_init+0x64/0x341 > [] ? child_rip+0xa/0x11 > [] ? kernel_init+0x0/0x341 > [] ? child_rip+0x0/0x11 > > > guess read_apic_id changing cuase some problem... genapic's read_apic_id() returns the actual apic id extracted from the APIC_ID register. And in some cases like UV, read_apic_id() returns completely different values from APIC ID register. Use the native apic register read, rather than genapic read_apic_id() in verify_local_APIC() And also, lapic_suspend() should also use native apic register read. Reported-by: Yinghai Lu Signed-off-by: Suresh Siddha Cc: "akpm@linux-foundation.org" Cc: "arjan@linux.intel.com" Cc: "andi@firstfloor.org" Cc: "ebiederm@xmission.com" Cc: "jbarnes@virtuousgeek.org" Cc: "steiner@sgi.com" Cc: "jeremy@goop.org" Signed-off-by: Ingo Molnar --- arch/x86/kernel/apic_64.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) Index: linux-2.6.26/arch/x86/kernel/apic_64.c =================================================================== --- linux-2.6.26.orig/arch/x86/kernel/apic_64.c +++ linux-2.6.26/arch/x86/kernel/apic_64.c @@ -629,10 +629,10 @@ int __init verify_local_APIC(void) /* * The ID register is read/write in a real APIC. */ - reg0 = read_apic_id(); + reg0 = apic_read(APIC_ID); apic_printk(APIC_DEBUG, "Getting ID: %x\n", reg0); apic_write(APIC_ID, reg0 ^ APIC_ID_MASK); - reg1 = read_apic_id(); + reg1 = apic_read(APIC_ID); apic_printk(APIC_DEBUG, "Getting ID: %x\n", reg1); apic_write(APIC_ID, reg0); if (reg1 != (reg0 ^ APIC_ID_MASK)) @@ -1136,7 +1136,7 @@ static int lapic_suspend(struct sys_devi maxlvt = lapic_get_maxlvt(); - apic_pm_state.apic_id = read_apic_id(); + apic_pm_state.apic_id = apic_read(APIC_ID); apic_pm_state.apic_taskpri = apic_read(APIC_TASKPRI); apic_pm_state.apic_ldr = apic_read(APIC_LDR); apic_pm_state.apic_dfr = apic_read(APIC_DFR);