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x86/apic: Prepare for unifying the interrupt delivery modes setup

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There are three places which initialize the interrupt delivery modes:

1) init_bsp_APIC() which is called early might setup the through-local-APIC
   virtual wire mode on non SMP systems.

2) In an SMP-capable system, native_smp_prepare_cpus() tries to switch to
   symmetric I/O model.

3) In UP system with UP_LATE_INIT=y, the local APIC and I/O APIC are set up
   in smp_init().

There is no technical reason to make these initializations at random places
and run the kernel with the potentially wrong mode through the early boot
stage, but it has a problematic side effect: The late switch to symmetric
I/O mode causes dump-capture kernel to hang when the kernel command line
option 'notsc' is active.

Provide a new function to unify that three positions. Preparatory patch to
initialize an interrupt mode directly.

Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: yinghai@kernel.org
Cc: bhe@redhat.com
Link: https://lkml.kernel.org/r/1505293975-26005-3-git-send-email-douly.fnst@cn.fujitsu.com
This commit is contained in:
Dou Liyang
2017-09-13 17:12:45 +08:00
committed by Thomas Gleixner
parent 0114a8e877
commit 4b1669e8d1
2 changed files with 18 additions and 0 deletions
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16
arch/x86/kernel/apic/apic.c
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@@ -1319,6 +1319,22 @@ void __init init_bsp_APIC(void)
apic_write(APIC_LVT1, value);
}
/* Init the interrupt delivery mode for the BSP */
void __init apic_intr_mode_init(void)
{
switch (apic_intr_mode_select()) {
case APIC_PIC:
pr_info("APIC: Keep in PIC mode(8259)\n");
return;
case APIC_VIRTUAL_WIRE:
pr_info("APIC: Switch to virtual wire mode setup\n");
return;
case APIC_SYMMETRIC_IO:
pr_info("APIC: Switch to symmectic I/O mode setup\n");
return;
}
}
static void lapic_setup_esr(void)
{
unsigned int oldvalue, value, maxlvt;