1 files changed, 9 insertions, 8 deletions

diff --git a/sys/i386/include/pcb.h b/sys/i386/include/pcb.h
index 1b14efa425b5..1385bfeeef31 100644
--- a/sys/i386/include/pcb.h
+++ b/sys/i386/include/pcb.h
@@ -44,16 +44,17 @@
 #include <machine/npx.h>
 
 /*
- * NB: The fields marked with (*) are used by kernel debuggers.  Their
- * ABI should be preserved.
+ * struct pcb is known to and used by kernel debuggers. Its layout must be kept
+ * stable. When adding extra fields that are accessed by kernel debuggers,
+ * debuggers should be backward compatible by using osreldate.
  */
 struct pcb {
-	int	pcb_edi;	/* (*) */
-	int	pcb_esi;	/* (*) */
-	int	pcb_ebp;	/* (*) */
-	int	pcb_esp;	/* (*) */
-	int	pcb_ebx;	/* (*) */
-	int	pcb_eip;	/* (*) */
+	int	pcb_edi;
+	int	pcb_esi;
+	int	pcb_ebp;
+	int	pcb_esp;
+	int	pcb_ebx;
+	int	pcb_eip;
 	struct segment_descriptor pcb_fsd;
 	struct segment_descriptor pcb_gsd;
 	int	pcb_ds;