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Date: Fri, 1 Feb 2008 23:07:16 +0100
From: Pavel Machek <pavel@....cz>
To: kernel list <linux-kernel@...r.kernel.org>
Cc: Linux-pm mailing list <linux-pm@...ts.osdl.org>,
"Rafael J. Wysocki" <rjw@...k.pl>
Subject: x86/.../trampoline_64.S racy?
Hi!
I'm trying to reuse trampoline_64.S for wakeup from ACPI s3... but I'm
getting some badness: If I insert delay loops into trampoline_64.S,
machine fails to boot; but I already increased cpu bootup delay to 200
seconds...
Is it possible that bootup is subtly racy somewhere?
diff --git a/arch/x86/kernel/smpboot_64.c b/arch/x86/kernel/smpboot_64.c
index aaf4e12..3961bcb 100644
--- a/arch/x86/kernel/smpboot_64.c
+++ b/arch/x86/kernel/smpboot_64.c
@@ -188,7 +188,7 @@ void __cpuinit smp_callin(void)
/*
* Waiting 2s total for startup (udelay is not yet working)
*/
- timeout = jiffies + 2*HZ;
+ timeout = jiffies + 200*HZ;
while (time_before(jiffies, timeout)) {
/*
* Has the boot CPU finished it's STARTUP sequence?
diff --git a/arch/x86/kernel/trampoline_64.S b/arch/x86/kernel/trampoline_64.S
index 4aedd0b..34fe9a7 100644
--- a/arch/x86/kernel/trampoline_64.S
+++ b/arch/x86/kernel/trampoline_64.S
@@ -24,12 +24,48 @@
* entries.
*/
+
#include <linux/linkage.h>
#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/msr.h>
#include <asm/segment.h>
+
+#define BEEP \
+ inb $97, %al; \
+ outb %al, $0x80; \
+ movb $3, %al; \
+ outb %al, $97; \
+ outb %al, $0x80; \
+ movb $-74, %al; \
+ outb %al, $67; \
+ outb %al, $0x80; \
+ movb $-119, %al; \
+ outb %al, $66; \
+ outb %al, $0x80; \
+ movb $15, %al; \
+ outb %al, $66;
+
+#define DISPLAY(x) \
+ pushl %eax ; \
+ movb $x, %al; \
+ outb %al, $0x80; \
+ popl %eax
+
+#define DISPLAY_UNSAFE(x) \
+ movb $x, %al; \
+ outb %al, $0x80; \
+
+#define DELAY_OK \
+ movl $0x30000000,%ecx ; \
+9: loopl 9b ;
+
+#define DELAY \
+ movl $1,%ecx ; \
+9: loopl 9b ;
+
+
/* We can free up trampoline after bootup if cpu hotplug is not supported. */
#ifndef CONFIG_HOTPLUG_CPU
.section .init.data, "aw", @progbits
@@ -55,6 +91,9 @@ r_base = .
# Setup stack
movw $(trampoline_stack_end - r_base), %sp
+ DISPLAY(0x70)
+ DELAY
+
call verify_cpu # Verify the cpu supports long mode
testl %eax, %eax # Check for return code
jnz no_longmode
@@ -78,6 +117,9 @@ r_base = .
lidtl tidt - r_base # load idt with 0, 0
lgdtl tgdt - r_base # load gdt with whatever is appropriate
+ DISPLAY(0x71)
+ DELAY
+
xor %ax, %ax
inc %ax # protected mode (PE) bit
lmsw %ax # into protected mode
@@ -91,6 +133,9 @@ startup_32:
movl $__KERNEL_DS, %eax # Initialize the %ds segment register
movl %eax, %ds
+ DISPLAY_UNSAFE(0x72)
+ DELAY
+
xorl %eax, %eax
btsl $5, %eax # Enable PAE mode
movl %eax, %cr4
@@ -109,6 +154,9 @@ startup_32:
btsl $0, %eax # Enable protected mode
movl %eax, %cr0
+ DISPLAY_UNSAFE(0x73)
+ DELAY
+
/*
* At this point we're in long mode but in 32bit compatibility mode
* with EFER.LME = 1, CS.L = 0, CS.D = 1 (and in turn
@@ -120,6 +168,9 @@ startup_32:
.code64
.balign 4
startup_64:
+ DISPLAY_UNSAFE(0x74)
+ DELAY
+
# Now jump into the kernel using virtual addresses
movq $secondary_startup_64, %rax
jmp *%rax
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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