Xen kernel fails to boot, d0v1 triple fault looks like the cuplrit

[Roger Pau Monné]

Please try to avoid top posting.

On Sat, May 19, 2018 at 03:45:41PM +0530, Pratyush Yadav wrote:
> Hi,
> 
> The line is
> 
> /usr/src/sys/amd64/amd64/mp_machdep.c:307

Hm, it seems like dbg_stack is not properly allocated. Can you please
try the above debug patch and paste the boot log?

---8<---
diff --git a/sys/amd64/amd64/mp_machdep.c b/sys/amd64/amd64/mp_machdep.c
index 301461420874..8854242b4bf5 100644
--- a/sys/amd64/amd64/mp_machdep.c
+++ b/sys/amd64/amd64/mp_machdep.c
@@ -304,6 +304,7 @@ init_secondary(void)
 
 	/* Save the per-cpu pointer for use by the DB# handler. */
 	np = ((struct nmi_pcpu *) &dbg_stack[PAGE_SIZE]) - 1;
+printf("ID %d dbg_stack: %p per-cpu: %p\n", cpu, dbg_stack, np);
 	np->np_pcpu = (register_t) pc;
 
 	wrmsr(MSR_FSBASE, 0);		/* User value */
@@ -403,6 +404,7 @@ native_start_all_aps(void)
 		    M_WAITOK | M_ZERO);
 		dbg_stack = (char *)kmem_malloc(kernel_arena, PAGE_SIZE,
 		    M_WAITOK | M_ZERO);
+printf("allocated dbg_stack: %p\n", dbg_stack);
 		dpcpu = (void *)kmem_malloc(kernel_arena, DPCPU_SIZE,
 		    M_WAITOK | M_ZERO);