diff options
| author | Baoquan He <[email protected]> | 2018-02-14 13:46:56 +0800 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2018-02-17 11:47:46 +0100 |
| commit | bee3204ec3c49f6f53add9c3962c9012a5c036fa (patch) | |
| tree | c242be4b2d21198f185461cd7d692fcf12b12297 | |
| parent | 51b146c572201e3c368e0baa3e565760aefcf25f (diff) | |
x86/apic: Set up through-local-APIC mode on the boot CPU if 'noapic' specified
Currently the kdump kernel becomes very slow if 'noapic' is specified.
Normal kernel doesn't have this bug.
Kernel parameter 'noapic' is used to disable IO-APIC in system for
testing or special purpose. Here the root cause is that in kdump
kernel LAPIC is disabled since commit:
522e664644 ("x86/apic: Disable I/O APIC before shutdown of the local APIC")
In this case we need set up through-local-APIC on boot CPU in
setup_local_APIC().
In normal kernel the legacy irq mode is enabled by the BIOS. If
it is virtual wire mode, the local-APIC has been enabled and set as
through-local-APIC.
Though we fixed the regression introduced by commit 522e664644,
to further improve robustness set up the through-local-APIC mode
explicitly, do not rely on the default boot IRQ mode.
Signed-off-by: Baoquan He <[email protected]>
Reviewed-by: Eric W. Biederman <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
[ Rewrote the changelog. ]
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | arch/x86/kernel/apic/apic.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 871018dd49a3..2ceac9f6c5d7 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1570,7 +1570,7 @@ static void setup_local_APIC(void) * TODO: set up through-local-APIC from through-I/O-APIC? --macro */ value = apic_read(APIC_LVT0) & APIC_LVT_MASKED; - if (!cpu && (pic_mode || !value)) { + if (!cpu && (pic_mode || !value || skip_ioapic_setup)) { value = APIC_DM_EXTINT; apic_printk(APIC_VERBOSE, "enabled ExtINT on CPU#%d\n", cpu); } else { |