[src/trunk]: src/sys/arch/amd64 Comments.

[uebayasi <uebayasi%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/68d7cfe12b80
branches:  trunk
changeset: 329168:68d7cfe12b80
user:      uebayasi <uebayasi%NetBSD.org@localhost>
date:      Mon May 12 22:50:03 2014 +0000

description:
Comments.

diffstat:

 sys/arch/amd64/amd64/machdep.c    |  5 +++--
 sys/arch/amd64/include/mcontext.h |  3 ++-
 2 files changed, 5 insertions(+), 3 deletions(-)

diffs (43 lines):

diff -r 13b6f2ca497e -r 68d7cfe12b80 sys/arch/amd64/amd64/machdep.c
--- a/sys/arch/amd64/amd64/machdep.c    Mon May 12 18:46:27 2014 +0000
+++ b/sys/arch/amd64/amd64/machdep.c    Mon May 12 22:50:03 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: machdep.c,v 1.210 2014/05/12 17:27:23 jakllsch Exp $   */
+/*     $NetBSD: machdep.c,v 1.211 2014/05/12 22:50:03 uebayasi Exp $   */
 
 /*-
  * Copyright (c) 1996, 1997, 1998, 2000, 2006, 2007, 2008, 2011
@@ -111,7 +111,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.210 2014/05/12 17:27:23 jakllsch Exp $");
+__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.211 2014/05/12 22:50:03 uebayasi Exp $");
 
 /* #define XENDEBUG_LOW  */
 
@@ -563,6 +563,7 @@
        if (onstack)
                sp = ((char *)l->l_sigstk.ss_sp + l->l_sigstk.ss_size);
        else
+               /* AMD64 ABI 128-bytes "red zone". */
                sp = (char *)tf->tf_rsp - 128;
 
        sp -= sizeof(struct sigframe_siginfo);
diff -r 13b6f2ca497e -r 68d7cfe12b80 sys/arch/amd64/include/mcontext.h
--- a/sys/arch/amd64/include/mcontext.h Mon May 12 18:46:27 2014 +0000
+++ b/sys/arch/amd64/include/mcontext.h Mon May 12 22:50:03 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: mcontext.h,v 1.17 2014/02/15 22:20:41 dsl Exp $        */
+/*     $NetBSD: mcontext.h,v 1.18 2014/05/12 22:50:03 uebayasi Exp $   */
 
 /*-
  * Copyright (c) 1999 The NetBSD Foundation, Inc.
@@ -66,6 +66,7 @@
 
 #define _UC_UCONTEXT_ALIGN     (~0xf)
 
+/* AMD64 ABI 128-bytes "red zone". */
 #define _UC_MACHINE_SP(uc)     ((uc)->uc_mcontext.__gregs[_REG_RSP] - 128)
 #define _UC_MACHINE_PC(uc)     ((uc)->uc_mcontext.__gregs[_REG_RIP])
 #define _UC_MACHINE_INTRV(uc)  ((uc)->uc_mcontext.__gregs[_REG_RAX])