Re: a question about how to debug this case in ftrace

[John Ogness]

On 2024-06-25, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> You may be interested in some work I'm doing that allows you to read
> the ring buffer from a previous kernel after a crash.
>
> https://lore.kernel.org/linux-trace-kernel/20240612231934.608252486@xxxxxxxxxxx/
>
> I also have a way to ask for any memory, that should be able to get the
> same location most times, via a "reserve_mem=" kernel command line
> parameter.
>
> https://lore.kernel.org/linux-trace-kernel/20240613233415.734483785@xxxxxxxxxxx/
>
> They are both destined for the next merge window. After that, I have
> one more patch that ties the two together, so that you can have a
> kernel command line of:
>
>  reserve_mem=12M:4096:trace trace_instance=bootmap@trace
>
> and then when you boot up, you would have a trace instance that would
> be mapped to that memory. If your machine doesn't clear memory after a
> crash, you can read the data from the crash on the next boot.

Nice. Thanks for the heads up. It will be nice to implement a "printk"
label as well. ;-)

John Ogness