How to printk synchronously

[Lucas Tanure]

Hi,

What about ftrace ? Documentation/trace/ftrace.txt

Thanks
Lucas

On Tue, Nov 26, 2019 at 8:08 PM aleave <aleave at protonmail.com> wrote:
>
> Hi everyone,
>
> I'm modifying kernel code and running into system dead-lock issues. I have printk statements to try to retrieve info about the freeze after I do a hard shutdown, but printk is asynchronous so /var/log/kern.log only shows NULL character gibberish instead (^@^@^@^@). Is there a way to make printk synchronous? I have looked at people using printk_sync and printk.synchronous variables as recently as 2017, but I don't see any reference to these anymore in the kernel version I have (5.4).
>
> Thanks for the help.
>
>
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