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vt: introduce and use vt_kmsg_redirect() function

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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>
This commit is contained in:
Bernhard Walle
2009-12-14 18:00:43 -08:00
committed by Linus Torvalds
parent c95d1e53ed
commit 5ada918b82
4 changed files with 55 additions and 12 deletions
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15
include/linux/vt.h
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@@ -84,4 +84,19 @@ struct vt_setactivate {
#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 */