one problem about using kdb 'ss' command

[Keith Owens]

"Zhou, Water" (on Mon, 26 Feb 2007 14:13:24 +0800) wrote:
>    Entering kdb (current=0xc460b550, pid 1125) duo to Breakpoint @0xc016ca90
>    kdb> ss
>
>    kdb_ss: pt_regs not available
>
>I think the problem is because of get_irq_regs() inline function
>return NULL when the breakpoint is touched. I don't know why ?

Correct, there are a couple of paths that do not call set_irq_regs().
Could you try this patch, it is against kdb-v4.4-2.6.20-common-4 but
should apply to 2.6.19 as well.  The patch compiles but I will not be
able to test it for for several hours.

Index: linux/kdb/kdbmain.c
===================================================================
--- linux.orig/kdb/kdbmain.c	2007-02-27 00:40:29.996600672 +1100
+++ linux/kdb/kdbmain.c	2007-02-27 00:40:18.934043094 +1100
@@ -1736,6 +1736,7 @@ kdb(kdb_reason_t reason, int error, stru
 	kdb_reason_t reason2 = reason;
 	int result = 0;	/* Default is kdb did not handle it */
 	int ss_event;
+	struct pt_regs *old_regs = NULL;
 	kdb_dbtrap_t db_result=KDB_DB_NOBPT;
 	preempt_disable();
 	atomic_inc(&kdb_event);
@@ -1745,6 +1746,11 @@ kdb(kdb_reason_t reason, int error, stru
 	case KDB_REASON_NMI:
 		KDB_FLAG_SET(CATASTROPHIC);	/* kernel state is dubious now */
 		break;
+	case KDB_REASON_ENTER:
+	case KDB_REASON_ENTER_SLAVE:
+		if (regs != get_irq_regs())
+			old_regs = set_irq_regs(regs);
+		break;
 	default:
 		break;
 	}
@@ -2060,6 +2066,8 @@ kdb(kdb_reason_t reason, int error, stru
 	if (!(KDB_STATE(DOING_SS) || KDB_STATE(SSBPT) || KDB_STATE(RECURSE))) {
 		KDB_DEBUG_STATE("kdb 15", result);
 		kdb_bp_install_local(regs);
+		if (old_regs)
+			set_irq_regs(old_regs);
 		KDB_STATE_CLEAR(KDB_CONTROL);
 	}
 

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