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authorThomas Meyer <thomas@m3y3r.de>2015-03-28 10:07:37 +0100
committerRichard Weinberger <richard@nod.at>2015-04-13 21:17:37 +0200
commit04a418495e0852263d77c4fb82adf470feaafef3 (patch)
tree55101ddcf7076f7f90a4957b3cdaed946289ccd7 /arch/um/kernel/kmsg_dump.c
parentfc9bea0e28db8cbfe0a08c1bfb1796bfd7adf49b (diff)
um: add a kmsg_dumper
Add a kmsg_dumper, that dumps the kmsg buffer to stdout, when no console is available. This an enables the printing of early panic() calls triggered in uml_postsetup(). When a panic() call happens so early in the UML kernel no earlyprintk/console is available yet, but with a kmsg_dumper in place the kernel message buffer will be outputted to the user, to give a better hint, of what the failure was. Signed-off-by: Thomas Meyer <thomas@m3y3r.de> Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/um/kernel/kmsg_dump.c')
-rw-r--r--arch/um/kernel/kmsg_dump.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c
new file mode 100644
index 000000000000..407d49251d6f
--- /dev/null
+++ b/arch/um/kernel/kmsg_dump.c
@@ -0,0 +1,43 @@
+#include <linux/kmsg_dump.h>
+#include <linux/console.h>
+#include <shared/init.h>
+#include <shared/kern.h>
+#include <os.h>
+
+static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
+ enum kmsg_dump_reason reason)
+{
+ static char line[1024];
+
+ size_t len = 0;
+ bool con_available = false;
+
+ /* only dump kmsg when no console is available */
+ if (!console_trylock())
+ return;
+
+ if (console_drivers != NULL)
+ con_available = true;
+
+ console_unlock();
+
+ if (con_available == true)
+ return;
+
+ printf("kmsg_dump:\n");
+ while (kmsg_dump_get_line(dumper, true, line, sizeof(line), &len)) {
+ line[len] = '\0';
+ printf("%s", line);
+ }
+}
+
+static struct kmsg_dumper kmsg_dumper = {
+ .dump = kmsg_dumper_stdout
+};
+
+int __init kmsg_dumper_stdout_init(void)
+{
+ return kmsg_dump_register(&kmsg_dumper);
+}
+
+__uml_postsetup(kmsg_dumper_stdout_init);