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author | Daniel Thompson <daniel.thompson@linaro.org> | 2014-07-16 14:30:13 +0100 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-07-17 18:19:40 -0700 |
commit | c8b29f049eb2645dd21e40a6613c09f15c731650 (patch) | |
tree | 1068dcafa1bcbe2959c4696fa8c010e9cdc7b51a /drivers/tty/serial/serial_core.c | |
parent | 3d1c90d48cbe335a47a6a5a05ff731a86eacf6fb (diff) | |
download | op-kernel-dev-c8b29f049eb2645dd21e40a6613c09f15c731650.zip op-kernel-dev-c8b29f049eb2645dd21e40a6613c09f15c731650.tar.gz |
tty: kgdb_nmi: Automatically manage tty enable
At present it is not possible to boot with the ttyNMI0 console treating
character input normally, instead character input triggers a prompt
telling the user how to trigger the knock detector and enter the
debugger. To use the console normally requires that kdb be entered and
the nmi_console command be used to enable the console (or if only kgdb
is present then gdb must directly manipulate the value of
kgdb_nmi_tty_enabled).
This patch automates the management of kgdb_nmi_tty_enabled by keeping
track of the number of file handles that are open for reading and using
that to determine how to tty should operate.
The approach means that:
1. Behaviour before init starts is unchanged.
2. If the userspace runs a getty or some other interactive process on
/dev/console (or explicitly on /dev/ttyNMI0) the tty will treat
character input like any other tty.
3. If the userspace doesn't use /dev/console or if it uses /dev/console
only to log messages (O_WRONLY) then the user prompt is retained.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-serial@vger.kernel.org
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: kgdb-bugreport@lists.sourceforge.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/serial_core.c')
0 files changed, 0 insertions, 0 deletions