Re: [PATCH] tracing: Record trace_clock in last_boot_info

From: Steven Rostedt
Date: Wed Apr 16 2025 - 11:12:39 EST


On Wed, 16 Apr 2025 23:46:38 +0900
"Masami Hiramatsu (Google)" <mhiramat@xxxxxxxxxx> wrote:

> Record trace_clock information in the trace_scratch area and show
> it via `last_boot_info` so that reader can docode the timestamp
> correctly.
> With this change, the first line of the last_boot_info becomes
> trace_clock which is used when the trace was recorded. E.g.
>
> /sys/kernel/tracing/instances/boot_mapped # cat last_boot_info
> trace_clock: mono
> ffffffff81000000 [kernel]
>

As this will not go in this cycle, which means tools may be built
around this.

Either we put it at the end, or we make it:

# trace_clock: mono
ffffffff81000000 [kernel]

Where "info" like "trace_clock" will be in the comment section, and all
non comments will be addresses.

Tooling can then just ignore the comment section, or read it for more
information.

-- Steve