Re: 2.6.14-rc3-rt10 crashes on boot

[John Rigg <lk@sound-man.co.uk>]

On Friday, October 7 Steven Rostedt wrote:

>Here's an addon patch to my last one.  I don't know x86_64 very well, but
>I believe the the asm is pretty much the same, so this patch removes the
>check for __i386__ and also defines STACK_WARN.

>Index: linux-rt-quilt/include/asm-x86_64/page.h
>===================================================================
>--- linux-rt-quilt.orig/include/asm-x86_64/page.h	2005-10-06 08:04:00.000000000 -0400
>+++ linux-rt-quilt/include/asm-x86_64/page.h	2005-10-07 15:34:20.000000000 -0400
>@@ -21,6 +21,8 @@
> #endif
> #define CURRENT_MASK (~(THREAD_SIZE-1))
>
>+#define STACK_WARN             (THREAD_SIZE/8)
>+
> #define LARGE_PAGE_MASK (~(LARGE_PAGE_SIZE-1))
> #define LARGE_PAGE_SIZE (1UL << PMD_SHIFT)
>
>Index: linux-rt-quilt/kernel/latency.c
>===================================================================
>--- linux-rt-quilt.orig/kernel/latency.c	2005-10-06 08:04:56.000000000 -0400
>+++ linux-rt-quilt/kernel/latency.c	2005-10-07 15:31:20.000000000 -0400
>@@ -377,7 +377,8 @@
> 	atomic_inc(&tr->disabled);
>
> 	/* Debugging check for stack overflow: is there less than 1KB free? */
>-#ifdef __i386__
>+#if 1 // def __i386__
>+	/* Hopefully this works on x86_64!  */
> 	__asm__ __volatile__("andl %%esp,%0" :
> 				"=r" (stack_left) : "0" (THREAD_SIZE - 1));
> #else

Steve, thanks for these patches. I got it to compile with 2.6.14-rc3-rt12
but had to change the assembly lines in (patched) latency.c to

__asm__ __volatile__("and %%rsp,%0" :
 				"=r" (stack_left) : "0" (THREAD_SIZE - 1));

ie. `and' instead of `andl' and `%%rsp' instead of `%%esp'.
Somebody who understands x86_64 assembly better than I do should probably check 
this before anyone tries using it.
While I was at it I changed a printk arg in line 335 of (patched) latency.c - 
I think the last %d should be %ld, ie. 

printk("| new stack-footprint maximum: %s/%d, %ld bytes (out of %ld bytes).\n",
	worst_stack_comm, worst_stack_pid, MAX_STACK-worst_stack_left, MAX_STACK); 

John