Commit 472a474c authored Mar 31, 2010 by Suresh Siddha Committed by Ingo Molnar Apr 02, 2010

x86: Fix double enable_IR_x2apic() call on SMP kernel on !SMP boards



Jan Grossmann reported kernel boot panic while booting SMP
kernel on his system with a single core cpu. SMP kernels call
enable_IR_x2apic() from native_smp_prepare_cpus() and on
platforms where the kernel doesn't find SMP configuration we
ended up again calling enable_IR_x2apic() from the
APIC_init_uniprocessor() call in the smp_sanity_check(). Thus
leading to kernel panic.

Don't call enable_IR_x2apic() and default_setup_apic_routing()
from APIC_init_uniprocessor() in CONFIG_SMP case.

NOTE: this kind of non-idempotent and assymetric initialization
sequence is rather fragile and unclean, we'll clean that up
in v2.6.35. This is the minimal fix for v2.6.34.

Reported-by:  <Jan.Grossmann@kielnet.net>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: <jbarnes@virtuousgeek.org>
Cc: <david.woodhouse@intel.com>
Cc: <weidong.han@intel.com>
Cc: <youquan.song@intel.com>
Cc: <Jan.Grossmann@kielnet.net>
Cc: <stable@kernel.org> # [v2.6.32.x, v2.6.33.x]
LKML-Reference: <1270083887.7835.78.camel@sbs-t61.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 51591e31

arch/x86/kernel/apic/apic.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1640,8 +1640,10 @@ int __init APIC_init_uniprocessor(void)
		}
		#endif

		#ifndef CONFIG_SMP
		enable_IR_x2apic();
		default_setup_apic_routing();
		#endif

		verify_local_APIC();
		connect_bsp_APIC();