On 12/07/14 01:47, Greg Kroah-Hartman wrote:
> On Fri, Jul 11, 2014 at 01:30:11PM +0100, Daniel Thompson wrote:
>> At present it is not possible to boot with the ttyNMI0 console treating
>> character input normally. To use the console 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).
>>
>> Introducing a module parameter makes the console much more usable.
>>
>> Signed-off-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
>> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>> Cc: Jiri Slaby <jslaby@xxxxxxx>
>> Cc: linux-serial@xxxxxxxxxxxxxxx
>> ---
>> drivers/tty/serial/kgdb_nmi.c | 5 +++++
>> 1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/tty/serial/kgdb_nmi.c b/drivers/tty/serial/kgdb_nmi.c
>> index cfadf29..9361d69 100644
>> --- a/drivers/tty/serial/kgdb_nmi.c
>> +++ b/drivers/tty/serial/kgdb_nmi.c
>> @@ -43,6 +43,11 @@ module_param_named(magic, kgdb_nmi_magic, charp, 0600);
>> MODULE_PARM_DESC(magic, "magic sequence to enter NMI debugger (default $3#33)");
>>
>> static bool kgdb_nmi_tty_enabled;
>> +module_param_named(tty, kgdb_nmi_tty_enabled, bool, 0600);
>> +MODULE_PARM_DESC(tty, "if set to false (default), characters received from "
>> + "the UART will be passed exclusively to the knock "
>> + "detector; when set to true characters will be passed "
>> + "both to the knock detector and to the TTY layer");
>
> Module options suck rocks through straws.
>
> Isn't there _any_ other way to determine this "dynamically"? How will
> someone know to set this option?
>
> Yeah, there are other options in this module, but please, why add more?
Thanks for the comment.
Yes. I think we can do this dynamically.
The two modes currently offered are:
1. characters bypass TTY layer and knock detector interactively prompts
for the knock ('Press $3#33 to enter debugger>')
2. characters are routed to TTY layer and to a (silenced) knock
detector
I think we might be able to select modes based on whether there is a
userspace process reading from the tty (i.e. if there is a getty then
act like a proper tty, if there is no getty allow prompting).
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