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

+

...
[ message continues ]

No, I just missed another place with timeout:
                /*

                 * Wait 5s total for a response

                 */

                for (timeout = 0; timeout < 5000000; timeout++) {

                        if (cpu_isset(cpu, cpu_callin_map))

                                break;  /* It has booted */

                        udelay(100);

                }
									Pavel
--

(english) http://www.livejournal.com/~pavelmachek

(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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