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Commit 4b1669e8 authored by Dou Liyang's avatar Dou Liyang Committed by Thomas Gleixner
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x86/apic: Prepare for unifying the interrupt delivery modes setup 



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: default avatarDou Liyang <douly.fnst@cn.fujitsu.com>
Signed-off-by: default avatarThomas 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
parent 0114a8e8

arch/x86/include/asm/apic.h

+2 −0
Original line number Diff line number Diff line
@@ -128,6 +128,7 @@ extern void disable_local_APIC(void); 
extern void lapic_shutdown(void);

extern void sync_Arb_IDs(void);

extern void init_bsp_APIC(void);

extern void apic_intr_mode_init(void);

extern void setup_local_APIC(void);

extern void init_apic_mappings(void);

void register_lapic_address(unsigned long address);
@@ -170,6 +171,7 @@ static inline void disable_local_APIC(void) { } 
# define setup_boot_APIC_clock x86_init_noop

# define setup_secondary_APIC_clock x86_init_noop

static inline void lapic_update_tsc_freq(void) { }

static inline void apic_intr_mode_init(void) { }

#endif /* !CONFIG_X86_LOCAL_APIC */



#ifdef CONFIG_X86_X2APIC

arch/x86/kernel/apic/apic.c

+16 −0
Original line number Diff line number Diff line
@@ -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;