instrumentation, was Re: core dump analysis

[Finn Thain <fthain@linux-m68k.org>]

[-- Attachment #1: Type: text/plain, Size: 1098 bytes --]

On Sun, 9 Apr 2023, Michael Schmitz wrote:

> Am 08.04.2023 um 00:06 schrieb Geert Uytterhoeven:
> >
> > On Fri, Apr 7, 2023 at 3:58 AM Michael Schmitz <wrote:
> >> The easiest way to do that is to log all wait and signal syscalls, as 
> >> well as process exit. That might alter timing if these log messages 
> >> go to the serial console though. Is that what you have in mind?
> >
> > Store to RAM, retrieve through a new /proc file?
> 
> Yes, that could be done, though I'd rather avoid duplicating a lot of 
> the generic message formatting code (printk and friends).
> 
> I'll have a look around ...
> 

A better solution might be be to port the existing instrumentation like 
ftrace, kprobes, uprobes etc. Might be a lot of work though. I wonder 
how portable that stuff is.

If you use printk, you could probably avoid most of the delays by enabling 
the dummy console. Then the kernel messages would be collected with dmesg, 
given a sufficiently large CONFIG_LOG_BUF_SHIFT. But it would be 
inconvenient to have no serial console available for the usual purposes.