Re: [PATCH 0/2] printk: Introduce loglevel bypass for pstore console

[Tzung-Bi Shih <tzungbi@kernel.org>]

On Wed, Sep 09, 2026 at 11:28:33AM +0200, Petr Mladek wrote:
> On Mon 2026-08-31 07:03:44, Tzung-Bi Shih wrote:
> > Currently, offline consoles (e.g., pstore_console backed by ramoops)
> > inherit the system's global console_loglevel.
> > 
> > In production environments, physical serial consoles (UARTs) are often
> > heavily rate-limited to prevent verbose messages from causing severe
> > execution bottlenecks.  Unfortunately, this identically silences the
> > pstore console.  When a kernel panic or lockup occurs, engineers are
> > left inspecting a crash dump that has been stripped of the verbose logs
> > that could have identified the root cause.
> > 
> > This series introduces CON_BYPASS_LOGLEVEL, a simple flag that allows
> > specialized offline consoles to request unsuppressed logs directly.
> > 
> > Patch 1 introduces the CON_BYPASS_LOGLEVEL flag.
> > Patch 2 adopts the flag in pstore_console.
> 
> I believe that a better solution for this problem would be adding
> the per-console loglevel feature, see
> https://lore.kernel.org/all/cover.1764272407.git.chris@chrisdown.name/
> 
> It is currently blocked by a cleanup of the console registration code,
> see https://lore.kernel.org/all/20260604101459.393162-1-pmladek@suse.com/
> 
> I am going to send v5 of the console registration code cleanup soon,
> hopefully later this week or the following week. It would be nice
> when it gets some more review.

Thanks for the context.  I completely agree that the per-console
loglevel is the proper long-term solution, and I understand that console
registration cleanup and the larger printk reworks are massive and
complex efforts.

Because those foundational changes naturally take time, I was wondering
if we could consider my approach as a narrow and localized exception
just for offline consoles like pstore.

Given that we already use LOG_FORCE_CON to bypass loglevels on a
per-message basis, introducing a symmetric per-console flag like
CON_BYPASS_LOGLEVEL might be an acceptable short-term solution.

Would you be open to a localized flag like this in the interim, or do
you strongly prefer to hold off until the full per-console loglevel
architecture lands?