Re: instrumentation, was Re: core dump analysis

Michael Schmitz
2023-04-11T04:56:59Z

Hi Finn,

Am 11.04.2023 um 12:20 schrieb Finn Thain:
> 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.

Can we disable the serial console after boot, by registering the dummy
console? Or will that just log messages to both?

Cheers,

Michael