Attempt to improve formatting and content of several comments for

amd64 and i386 MD code.

Based on suggestions by:	bde
MFC after:	1 week

3 files changed, 13 insertions, 13 deletions

diff --git a/sys/i386/i386/trap.c b/sys/i386/i386/trap.c
index b241757..6e7f1d9 100644
--- a/sys/i386/i386/trap.c
+++ b/sys/i386/i386/trap.c
@@ -1065,9 +1065,8 @@ cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 #include "../../kern/subr_syscall.c"
 
 /*
- *	syscall -	system call request C handler
- *
- *	A system call is essentially treated as a trap.
+ * syscall - system call request C handler.  A system call is
+ * essentially treated as a trap by reusing the frame layout.
  */
 void
 syscall(struct trapframe *frame)
diff --git a/sys/i386/include/signal.h b/sys/i386/include/signal.h
index 7a5f876..c636c2c 100644
--- a/sys/i386/include/signal.h
+++ b/sys/i386/include/signal.h
@@ -46,16 +46,17 @@ typedef int sig_atomic_t;
 #include <machine/trap.h>	/* codes for SIGILL, SIGFPE */
 
 /*
- * Only the kernel should need these old type definitions.
- */
-#if defined(_KERNEL) && defined(COMPAT_43)
-/*
  * Information pushed on stack when a signal is delivered.
  * This is used by the kernel to restore state following
  * execution of the signal handler.  It is also made available
  * to the handler to allow it to restore state properly if
  * a non-standard exit is performed.
  */
+
+#if defined(_KERNEL) && defined(COMPAT_43)
+/*
+ * Only the kernel should need these old type definitions.
+ */
 struct osigcontext {
 	int	sc_onstack;		/* sigstack state to restore */
 	osigset_t sc_mask;		/* signal mask to restore */
@@ -83,7 +84,7 @@ struct osigcontext {
 
 /*
  * The sequence of the fields/registers in struct sigcontext should match
- * those in mcontext_t.
+ * those in mcontext_t and struct trapframe.
  */
 struct sigcontext {
 	struct __sigset sc_mask;	/* signal mask to restore */
@@ -109,8 +110,8 @@ struct sigcontext {
 	int	sc_ss;
 	int	sc_len;			/* sizeof(mcontext_t) */
 	/*
-	 * XXX - See <machine/ucontext.h> and <machine/npx.h> for
-	 *       the following fields.
+	 * See <machine/ucontext.h> and <machine/npx.h> for
+	 * the following fields.
 	 */
 	int	sc_fpformat;
 	int	sc_ownedfp;
diff --git a/sys/i386/include/ucontext.h b/sys/i386/include/ucontext.h
index d8657d3..d9f8344 100644
--- a/sys/i386/include/ucontext.h
+++ b/sys/i386/include/ucontext.h
@@ -33,9 +33,9 @@
 
 typedef struct __mcontext {
 	/*
-	 * The first 20 fields must match the definition of
-	 * sigcontext. So that we can support sigcontext
-	 * and ucontext_t at the same time.
+	 * The definition of mcontext_t shall match the layout of
+	 * struct sigcontext after the sc_mask member.  So that we can
+	 * support sigcontext and ucontext_t at the same time.
 	 */
 	__register_t	mc_onstack;	/* XXX - sigcontext compat. */
 	__register_t	mc_gs;		/* machine state (struct trapframe) */