Messages in this thread | | | Date | Sun, 7 Jun 2009 12:28:07 -0700 | Subject | Re: [PATCH] x86: fix dummy apic read/write warning | From | Yinghai Lu <> |
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On Sun, Jun 7, 2009 at 12:01 AM, Cyrill Gorcunov<gorcunov@gmail.com> wrote: > [Yinghai Lu - Sat, Jun 06, 2009 at 03:16:38PM -0700] > | ingo got > | [ 0.000000] Using APIC driver default > | [ 0.000000] SMP: Allowing 1 CPUs, 0 hotplug CPUs > | [ 0.000000] Local APIC disabled by BIOS -- you can enable it with "lapic" > | [ 0.000000] APIC: disable apic facility > | [ 0.000000] ------------[ cut here ]------------ > | [ 0.000000] WARNING: at arch/x86/kernel/apic/apic.c:254 native_apic_read_dummy+0x2d/0x3b() > | [ 0.000000] Hardware name: HP OmniBook PC > | > | we have wrong check in dummy read and write. > | [we only test on system that have APIC with "disableapic"...] > | > | Signed-off-by: yinghai Lu <yinghai@kernel.org> > | > | --- > | arch/x86/kernel/apic/apic.c | 4 ++-- > | 1 file changed, 2 insertions(+), 2 deletions(-) > | > | Index: linux-2.6/arch/x86/kernel/apic/apic.c > | =================================================================== > | --- linux-2.6.orig/arch/x86/kernel/apic/apic.c > | +++ linux-2.6/arch/x86/kernel/apic/apic.c > | @@ -246,12 +246,12 @@ static int modern_apic(void) > | */ > | static void native_apic_write_dummy(u32 reg, u32 v) > | { > | - WARN_ON_ONCE((cpu_has_apic || !disable_apic)); > | + WARN_ON_ONCE((cpu_has_apic && !disable_apic)); > | } > | > | static u32 native_apic_read_dummy(u32 reg) > | { > | - WARN_ON_ONCE((cpu_has_apic || !disable_apic)); > | + WARN_ON_ONCE((cpu_has_apic && !disable_apic)); > | return 0; > | } > | > | > > No Yinghai, this is wrong. native_apic_write_dummy is not > admissible to be called after apic->write has been NOP'ified. > > If a site calls for apic->write after apic_disable() it's > a plain *bug* in caller. So we should continute warning if > cpu_has_apic _or_ !disable_apic.
ok, just change it to
WARN_ON_ONCE(1);
there.
> > Though since for SMP compiled kernel we still rely on > apic->read the snippet is to be changed to (cpu_has_apic && !disable_apic) > indeed.
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