From: Scott Moser <smoser@redhat.com>
Subject: [RHEL5.1 PATCH] bz229593 Fix xmon=off and cleanup xmon initialization
Date: Wed, 30 May 2007 10:19:46 -0400 (EDT)
Bugzilla: 229593
Message-Id: <Pine.LNX.4.64.0705301018300.5134@squad5-lp1.lab.boston.redhat.com>
Changelog: [ppc] Fix xmon=off and cleanup xmon initialization


RHBZ#: 229593
------
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=229593

Description:
------------
  [POWERPC] Fix xmon=off and cleanup xmon initialisation
  
  My patch to make the early xmon logic work with earlier early param
  parsing (480f6f35a149802a94ad5c1a2673ed6ec8d2c158) breaks xmon=off.
  
  No one does this obviously as xmon rocks, but it should really work
  as documented.
  
  While fixing that it struck me that we could move the xmon param
  handling into xmon.c, and also consolidate the
  xmon_init()/do_early_xmon logic into xmon_setup(). This means
  xmon=early drops into xmon a little earlier on 32-bit, but it
  seems to work just fine.
  
  Tested on PSERIES and CLASSIC32.
  
  Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
  Signed-off-by: Paul Mackerras <paulus@samba.org>

RHEL Version Found:
-------------------
bug against 5.0

Upstream Status:
----------------
This code is upstream in 2.6.19
git commit [1] 476792839467c08ddeedd8b44a7423d415b68259


Test Status:
------------
These patches have been built against 2.6.18-19.el5, and successfully
built in brew task 794835 [2].

Testing has been done by Chandru Siddalingappa of IBM.  The system
successfully booted into a kdump kernel without entering into xmon when
'xmon=off' was passed on the command line. 

Proposed Patch:
----------------
Please review and ACK for RHEL5.1

-- 
[1] http://git.kernel.org/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=476792839467c08ddeedd8b44a7423d415b68259
[2] http://brewweb.devel.redhat.com/brew/taskinfo?taskID=794835

---
 arch/powerpc/kernel/setup-common.c |   21 ---------------------
 arch/powerpc/kernel/setup_32.c     |    8 ++------
 arch/powerpc/kernel/setup_64.c     |   12 ++++--------
 arch/powerpc/xmon/xmon.c           |   35 +++++++++++++++++++++++++++++++++++
 include/asm-powerpc/xmon.h         |    6 +++++-
 5 files changed, 46 insertions(+), 36 deletions(-)

Index: linux-2.6.18.ppc64/arch/powerpc/kernel/setup-common.c
===================================================================
--- linux-2.6.18.ppc64.orig/arch/powerpc/kernel/setup-common.c
+++ linux-2.6.18.ppc64/arch/powerpc/kernel/setup-common.c
@@ -442,27 +442,6 @@ void __init smp_setup_cpu_maps(void)
 }
 #endif /* CONFIG_SMP */
 
-int __initdata do_early_xmon;
-#ifdef CONFIG_XMON
-static int __init early_xmon(char *p)
-{
-	/* ensure xmon is enabled */
-	if (p) {
-		if (strncmp(p, "on", 2) == 0)
-			xmon_init(1);
-		if (strncmp(p, "off", 3) == 0)
-			xmon_init(0);
-		if (strncmp(p, "early", 5) != 0)
-			return 0;
-	}
-	xmon_init(1);
-	do_early_xmon = 1;
-
-	return 0;
-}
-early_param("xmon", early_xmon);
-#endif
-
 static __init int add_pcspkr(void)
 {
 	struct device_node *np;
Index: linux-2.6.18.ppc64/arch/powerpc/kernel/setup_32.c
===================================================================
--- linux-2.6.18.ppc64.orig/arch/powerpc/kernel/setup_32.c
+++ linux-2.6.18.ppc64/arch/powerpc/kernel/setup_32.c
@@ -246,12 +246,11 @@ void __init setup_arch(char **cmdline_p)
 
 	smp_setup_cpu_maps();
 
-#ifdef CONFIG_XMON_DEFAULT
-	xmon_init(1);
-#endif
 	/* Register early console */
 	register_early_udbg_console();
 
+	xmon_setup();
+
 #if defined(CONFIG_KGDB)
 	if (ppc_md.kgdb_map_scc)
 		ppc_md.kgdb_map_scc();
@@ -288,9 +287,6 @@ void __init setup_arch(char **cmdline_p)
 	init_mm.end_data = (unsigned long) _edata;
 	init_mm.brk = klimit;
 
-	if (do_early_xmon)
-		debugger(NULL);
-
 	/* set up the bootmem stuff with available memory */
 	do_init_bootmem();
 	if ( ppc_md.progress ) ppc_md.progress("setup_arch: bootmem", 0x3eab);
Index: linux-2.6.18.ppc64/arch/powerpc/kernel/setup_64.c
===================================================================
--- linux-2.6.18.ppc64.orig/arch/powerpc/kernel/setup_64.c
+++ linux-2.6.18.ppc64/arch/powerpc/kernel/setup_64.c
@@ -406,18 +406,14 @@ void __init setup_system(void)
 	find_legacy_serial_ports();
 
 	/*
-	 * Initialize xmon
-	 */
-#ifdef CONFIG_XMON_DEFAULT
-	xmon_init(1);
-#endif
-	/*
 	 * Register early console
 	 */
 	register_early_udbg_console();
 
-	if (do_early_xmon)
-		debugger(NULL);
+	/*
+	 * Initialize xmon
+	 */
+	xmon_setup();
 
 	check_smt_enabled();
 	smp_setup_cpu_maps();
Index: linux-2.6.18.ppc64/arch/powerpc/xmon/xmon.c
===================================================================
--- linux-2.6.18.ppc64.orig/arch/powerpc/xmon/xmon.c
+++ linux-2.6.18.ppc64/arch/powerpc/xmon/xmon.c
@@ -2,6 +2,8 @@
  * Routines providing a simple monitor for use on the PowerMac.
  *
  * Copyright (C) 1996-2005 Paul Mackerras.
+ * Copyright (C) 2001 PPC64 Team, IBM Corp
+ * Copyrignt (C) 2006 Michael Ellerman, IBM Corp
  *
  *      This program is free software; you can redistribute it and/or
  *      modify it under the terms of the GNU General Public License
@@ -143,6 +145,8 @@ static const char *getvecname(unsigned l
 
 extern int print_insn_powerpc(unsigned long, unsigned long, int);
 
+int xmon_no_auto_backtrace;
+
 extern void xmon_enter(void);
 extern void xmon_leave(void);
 
@@ -2587,3 +2591,34 @@ static int __init setup_xmon_sysrq(void)
 }
 __initcall(setup_xmon_sysrq);
 #endif /* CONFIG_MAGIC_SYSRQ */
+
+int __initdata xmon_early, xmon_off;
+
+static int __init early_parse_xmon(char *p)
+{
+	if (!p || strncmp(p, "early", 5) == 0) {
+		/* just "xmon" is equivalent to "xmon=early" */
+		xmon_init(1);
+		xmon_early = 1;
+	} else if (strncmp(p, "on", 2) == 0)
+		xmon_init(1);
+	else if (strncmp(p, "off", 3) == 0)
+		xmon_off = 1;
+	else if (strncmp(p, "nobt", 4) == 0)
+		xmon_no_auto_backtrace = 1;
+	else
+		return 1;
+
+	return 0;
+}
+early_param("xmon", early_parse_xmon);
+
+void __init xmon_setup(void)
+{
+#ifdef CONFIG_XMON_DEFAULT
+	if (!xmon_off)
+		xmon_init(1);
+#endif
+	if (xmon_early)
+		debugger(NULL);
+}
Index: linux-2.6.18.ppc64/include/asm-powerpc/xmon.h
===================================================================
--- linux-2.6.18.ppc64.orig/include/asm-powerpc/xmon.h
+++ linux-2.6.18.ppc64/include/asm-powerpc/xmon.h
@@ -6,7 +6,11 @@ struct pt_regs;
 
 extern int xmon(struct pt_regs *excp);
 extern void xmon_printf(const char *fmt, ...);
-extern void xmon_init(int);
+#ifdef CONFIG_XMON
+extern void xmon_setup(void);
+#else
+static inline void xmon_setup(void) { };
+#endif
 
 #endif
 #endif