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-rw-r--r--Documentation/kernel-parameters.txt6
-rw-r--r--include/linux/kmsg_dump.h9
-rw-r--r--kernel/printk.c6
3 files changed, 19 insertions, 2 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 033d4e69b43b..d99fd9c0ec0e 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2211,6 +2211,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
default: off.
+ printk.always_kmsg_dump=
+ Trigger kmsg_dump for cases other than kernel oops or
+ panics
+ Format: <bool> (1/Y/y=enable, 0/N/n=disable)
+ default: disabled
+
printk.time= Show timing data prefixed to each printk message line
Format: <bool> (1/Y/y=enable, 0/N/n=disable)
diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
index fee66317e071..35f7237ec972 100644
--- a/include/linux/kmsg_dump.h
+++ b/include/linux/kmsg_dump.h
@@ -15,13 +15,18 @@
#include <linux/errno.h>
#include <linux/list.h>
+/*
+ * Keep this list arranged in rough order of priority. Anything listed after
+ * KMSG_DUMP_OOPS will not be logged by default unless printk.always_kmsg_dump
+ * is passed to the kernel.
+ */
enum kmsg_dump_reason {
- KMSG_DUMP_OOPS,
KMSG_DUMP_PANIC,
+ KMSG_DUMP_OOPS,
+ KMSG_DUMP_EMERG,
KMSG_DUMP_RESTART,
KMSG_DUMP_HALT,
KMSG_DUMP_POWEROFF,
- KMSG_DUMP_EMERG,
};
/**
diff --git a/kernel/printk.c b/kernel/printk.c
index 13c0a1143f49..32690a0b7a18 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -702,6 +702,9 @@ static bool printk_time = 0;
#endif
module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
+static bool always_kmsg_dump;
+module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
+
/* Check if we have any console registered that can be called early in boot. */
static int have_callable_console(void)
{
@@ -1732,6 +1735,9 @@ void kmsg_dump(enum kmsg_dump_reason reason)
unsigned long l1, l2;
unsigned long flags;
+ if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
+ return;
+
/* Theoretically, the log could move on after we do this, but
there's not a lot we can do about that. The new messages
will overwrite the start of what we dump. */