amd64 profiling kernel build failure

[Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>]

Hi,

I try to build amd64 profiling kernel in accordance with the following
guide.
    http://www.netbsd.org/docs/kernel/profiling/

Howerver, GENERIC.PROF kernel build failure. I make the following
patch to fix this build failure.
====================
diff --git a/sys/arch/amd64/include/profile.h b/sys/arch/amd64/include/profile.h
index f760594..24ea606 100644
--- a/sys/arch/amd64/include/profile.h
+++ b/sys/arch/amd64/include/profile.h
@@ -85,7 +85,7 @@ __asm(" .globl __mcount               \n"                     \
 
 #ifdef _KERNEL
 #ifdef MULTIPROCESSOR
-__cpu_simple_lock_t __mcount_lock;
+extern __cpu_simple_lock_t __mcount_lock;
 
 static inline void
 MCOUNT_ENTER_MP(void)
diff --git a/sys/kern/subr_prof.c b/sys/kern/subr_prof.c
index 1f9136e..fbc0e17 100644
--- a/sys/kern/subr_prof.c
+++ b/sys/kern/subr_prof.c
@@ -48,6 +48,10 @@ __KERNEL_RCSID(0, "$NetBSD: subr_prof.c,v 1.47 2014/07/10 21:13:52 christos Exp
 #include <sys/malloc.h>
 #include <sys/gmon.h>
 
+#ifdef MULTIPROCESSOR
+__cpu_simple_lock_t __mcount_lock;
+#endif
+
 MALLOC_DEFINE(M_GPROF, "gprof", "kernel profiling buffer");
 
 /*
====================

Could you comment this patch?


Thanks,

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Device Engineering Section,
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Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>