vt: introduce and use vt_kmsg_redirect() function
The kernel offers with TIOCL_GETKMSGREDIRECT ioctl() the possibility to
redirect the kernel messages to a specific console.
However, since it's not possible to switch to the kernel message console
after a panic(), it would be nice if the kernel would print the panic
message on the current console.
This patch series adds a new interface to access the global kmsg_redirect
variable by a function to be able to use it in code where
CONFIG_VT_CONSOLE is not set (kernel/panic.c).
This patch:
Instead of using and exporting a global value kmsg_redirect, introduce a
function vt_kmsg_redirect() that both can set and return the console where
messages are printed.
Change all users of kmsg_redirect (the VT code itself and kernel/power.c)
to the new interface.
The main advantage is that vt_kmsg_redirect() can also be used when
CONFIG_VT_CONSOLE is not set.
Signed-off-by: Bernhard Walle <bernhard@bwalle.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/vt.h b/include/linux/vt.h
index 7ffa11f..3fb9944 100644
--- a/include/linux/vt.h
+++ b/include/linux/vt.h
@@ -84,4 +84,19 @@
#define VT_SETACTIVATE 0x560F /* Activate and set the mode of a console */
+#ifdef CONFIG_VT_CONSOLE
+
+extern int vt_kmsg_redirect(int new);
+
+#else
+
+static inline int vt_kmsg_redirect(int new)
+{
+ return 0;
+}
+
+#endif
+
+#define vt_get_kmsg_redirect() vt_kmsg_redirect(-1)
+
#endif /* _LINUX_VT_H */