Re: kgdb support in vanilla 2.6.2

[Amit S. Kale]

On Thursday 04 Mar 2004 10:48 am, Andrew Morton wrote:
> "Amit S. Kale" <amitkale@xxxxxxxxxxxxx> wrote:
> > Flashing keyboard lights is easy on x86 and x86_64 platforms.
>
> Please, no keyboards.  Some people want to be able to use kgdboe
> to find out why machine number 324 down the corridor just died.
>
> How about just doing
>
>
> char *why_i_crashed;
>
>
> {
> 	...
> 	if (expr1)
> 		why_i_crashed = "hit a BUG";
> 	else if (expr2)
> 		why_i_crashed = "divide by zero";
> 	else ...
> }
>
> then provide a gdb macro which prints out the string at *why_i_crashed?

If we can afford to do this (in terms of actions that can be done with the 
machine being unstable) we can certainly print a console message through gdb.

A stub is free to send console messages to gdb at any time. We can send a 
"'O'hex(Page fault at 0x1234)" packet to gdb regardless of whether 
CONFIG_KGDB_CONSOLE is configured in. This way kgdb will send this packet to 
gdb and then immediately report a segfault/trap. To a user it'll appear as a 
message printed from gdb "Page fault at 0x1234" followed by gdb showing a 
SIGSEGV etc. The gdb console message should print information other than a 
signal number.

-Amit

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