Subject: [patch] uml core on panic
From: Gerd Knorr <kraxel@suse.de>

allow the uml kernel throw cores for crash analysis later on.

Index: linux-2.6.11/arch/um/kernel/Makefile
===================================================================
--- linux-2.6.11.orig/arch/um/kernel/Makefile	2005-04-19 14:37:57.000000000 +0200
+++ linux-2.6.11/arch/um/kernel/Makefile	2005-04-19 14:39:02.000000000 +0200
@@ -12,7 +12,7 @@ obj-y = checksum.o config.o exec_kern.o 
 	sigio_user.o sigio_kern.o signal_kern.o signal_user.o smp.o \
 	syscall_kern.o syscall_user.o sysrq.o sys_call_table.o tempfile.o \
 	time.o time_kern.o tlb.o trap_kern.o trap_user.o uaccess_user.o \
-	um_arch.o umid.o user_util.o
+	um_arch.o umid.o user_util.o core-on-panic.o
 
 obj-$(CONFIG_BLK_DEV_INITRD) += initrd_kern.o initrd_user.o
 obj-$(CONFIG_GPROF)	+= gprof_syms.o
Index: linux-2.6.11/arch/um/kernel/core-on-panic.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.11/arch/um/kernel/core-on-panic.c	2005-04-19 14:39:02.000000000 +0200
@@ -0,0 +1,64 @@
+/*
+ * allow user mode linux kernels dump core on kernel panics,
+ * for later analysis of the crash.
+ *
+ * (c) 2004 Gerd Knorr + D. Bahi
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/notifier.h>
+
+#include "init.h"
+#include "os.h"
+
+static int core_on_panic_func(struct notifier_block *self, unsigned long unused1,
+		              void *unused2)
+{
+	static int recurse = 0;
+
+        /* cleanup so we have less to cleanup [linux] on the host */
+	/* could panic in uml_cleanup though so we need a check */
+        if (0 == recurse++)
+		uml_cleanup();
+
+	/* to prevent keyboard from causing terminal to spew during dump */
+	block_signals();
+
+	/* actually dump ... */
+	abort();
+
+	/* not reached */
+	return 0;
+}
+
+static struct notifier_block core_on_panic_notifier = {
+	.notifier_call 		= core_on_panic_func,
+	.priority 		= 1,
+};
+
+static int core_on_panic = 0;
+
+static int __init core_on_panic_setup(char *str)
+{
+	core_on_panic = 1;
+	return 0;
+}
+
+static int __init core_on_panic_init(void)
+{
+	if (core_on_panic)
+		notifier_chain_register(&panic_notifier_list, &core_on_panic_notifier);
+	return 0;
+}
+
+__initcall(core_on_panic_init);
+__setup("coreonpanic", core_on_panic_setup);
+__uml_help(core_on_panic_setup,
+	"coreonpanic\n"
+	"    This flag make it so that UML will dump core on a kernel panic or segfault.\n"
+	"    Shell environment restrictions on cores (limit or ulimit) still apply.\n"
+	"\n"
+	"    Beware that your UML will not reboot with this flag.\n"
+	"\n"
+);
+