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Date: Fri, 5 Jan 2018 11:26:57 +0800 From: Baoquan He <bhe@...hat.com> To: linux-kernel@...r.kernel.org Cc: mingo@...hat.com, tglx@...utronix.de, hpa@...or.com, x86@...nel.org, douly.fnst@...fujitsu.com, rostedt@...dmis.org, jgross@...e.com, peterz@...radead.org, uobergfe@...hat.com, joro@...tes.org Subject: Re: [PATCH 1/3] x86/apic: Set up through LAPIC on boot CPU's LINT0 if ioapic is disabled to kexec/kdump kernel Sorry, my git send-email config seems incorrect. The patch subject is not right. So NACK this series, will repost v2. On 01/05/18 at 11:22am, Baoquan He wrote: > Kdump kernel will become very slow if 'noapic' is specified in kernel > command line. Normal kernel doesn't have this issue. > > This is because the legacy irq mode is disabled in crashed kernel before > jump jump to kdump kernel since commit 522e66464467 ("x86/apic: Disable I/O > APIC before shutdown of the local APIC") is merged. While in normal kernel, > the legacy irq mode has been set in BIOS. > > So we need set the delivery mode AS ExtINT for LVT0 of boot CPU's LAPIC > explicitly if IO-APIC is disabled, to set up through-local-APIC. > > Signed-off-by: Baoquan He <bhe@...hat.com> > --- > arch/x86/kernel/apic/apic.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c > index 880441f24146..7e613fb90630 100644 > --- a/arch/x86/kernel/apic/apic.c > +++ b/arch/x86/kernel/apic/apic.c > @@ -1521,7 +1521,7 @@ 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 { > -- > 2.5.5 >
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