[PATCH v8 12/13] 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.

call it behind timers init, which meets the above conditions.

Signed-off-by: Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>
---
 arch/x86/kernel/apic/apic.c | 2 --
 arch/x86/kernel/smpboot.c   | 2 --
 arch/x86/kernel/time.c      | 5 +++++
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 47b67f9..7fb5cde 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2471,8 +2471,6 @@ void __init apic_bsp_setup(bool upmode)
 #ifdef CONFIG_UP_LATE_INIT
 void __init up_late_init(void)
 {
-	x86_init.irqs.intr_mode_init();
-
 	if (apic_intr_mode == APIC_PIC)
 		return;
 
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 2e0eaf2..4f63afc 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1293,8 +1293,6 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
 
 	set_cpu_sibling_map(0);
 
-	x86_init.irqs.intr_mode_init();
-
 	smp_sanity_check();
 
 	switch (apic_intr_mode) {
diff --git a/arch/x86/kernel/time.c b/arch/x86/kernel/time.c
index e0754cd..3ceb834 100644
--- a/arch/x86/kernel/time.c
+++ b/arch/x86/kernel/time.c
@@ -84,6 +84,11 @@ 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.intr_mode_init();
 	tsc_init();
 }
 
-- 
2.5.5