[RFC PATCH v4 04/12] x86/time: Initialize interrupt mode behind timer init

[Dou Liyang]

In start_kernel(), firstly, it works on the default interrupy mode, then
switch to the final mode. Normally, Booting with BIOS reset is OK.

But, At dump-capture kernel, it boot up without BIOS reset, default mode
may not be compatible with the actual registers, that causes the delivery
interrupt to fail.

Try to set up the final mode as soon as possible. according to the parts
which split from that initialization:

1) Set up the APIC/IOAPIC (including testing whether the timer
   interrupt works)

2) Calibrate TSC

3) Set up the local APIC timer

-- From Thomas Gleixner

Initializing the mode should be earlier than calibrating TSC as soon as
possible and needs testing whether the timer interrupt works at the same
time.

Add interrupt_mode_init to x86_init_ops, and call it behind timers init,
which meets the above conditions.

Signed-off-by: Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>
---
V3 --> V4:
  -Move interrupt_mode_init to x86_init_ops instead of the use of header
files

 arch/x86/include/asm/x86_init.h | 2 ++
 arch/x86/kernel/time.c          | 7 +++++++
 arch/x86/kernel/x86_init.c      | 1 +
 3 files changed, 10 insertions(+)

diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index 7ba7e90..ce8a712 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -50,11 +50,13 @@ struct x86_init_resources {
  *				are set up.
  * @intr_init:			interrupt init code
  * @trap_init:			platform specific trap setup
+ * @interrupt_mode_init:	interrupt delivery mode setup
  */
 struct x86_init_irqs {
 	void (*pre_vector_init)(void);
 	void (*intr_init)(void);
 	void (*trap_init)(void);
+	void (*interrupt_mode_init)(void);
 };
 
 /**
diff --git a/arch/x86/kernel/time.c b/arch/x86/kernel/time.c
index d39c091..bbf2821 100644
--- a/arch/x86/kernel/time.c
+++ b/arch/x86/kernel/time.c
@@ -84,6 +84,13 @@ void __init hpet_time_init(void)
 static __init void x86_late_time_init(void)
 {
 	x86_init.timers.timer_init();
+
+	/*
+	 * After PIT/HPET timers init, select and setup
+	 * the final interrupt mode for delivering IRQs.
+	 */
+	x86_init.irqs.interrupt_mode_init();
+
 	tsc_init();
 }
 
diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index a088b2c..bcb3173 100644
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -55,6 +55,7 @@ struct x86_init_ops x86_init __initdata = {
 		.pre_vector_init	= init_ISA_irqs,
 		.intr_init		= native_init_IRQ,
 		.trap_init		= x86_init_noop,
+		.interrupt_mode_init	= apic_interrupt_mode_init
 	},
 
 	.oem = {
-- 
2.5.5