Re: [PATCH v2 2/4] printk: deprecate boot_delay in favour of printk_delay

[Petr Mladek]

On Tue 2026-06-30 17:35:58, Andrew Murray wrote:
> The boot_delay (BOOT_PRINTK_DELAY) kernel parameter and printk_delay sysctl
> are two distinct mechanisms for providing similar functionality which add a
> delay prior to each printed printk message.
> 
> boot_delay provides a kernel parameter for delaying printk output from
> kernel start through to boot (SYSTEM_RUNNING), whereas printk_delay is
> configurable only via sysctl and thus is only used post boot.
> 
> Let's deprecate the boot_delay feature in favour of printk_delay. In order
> to preserve functionality, we'll also extend printk_delay such that it can
> additionally configured via an early kernel parameter.
> 
> Behavior change:
> 
> The delay enabled by both "boot_delay" and "printk_delay" continues
> working even in SYSTEM_RUNNING state. It must be explicitly stopped
> by setting printk_delay=0 via sysctl.
> 
> The delay is skipped when the message is suppressed in all system
> states. It used to skipped only for the boot_delay.
> 
> Signed-off-by: Andrew Murray <amurray@xxxxxxxxxxxxxxxxxxxx>

Looks good to me:

Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>

Note that Sashiko AI warns about possible problems with negative
printk_delay values, see
https://sashiko.dev/#/patchset/20260630-deprecate_boot_delay-v2-0-f9883d36aa4b%40thegoodpenguin.co.uk

But they should be handled in both the early parameter
and sysctl interface by the "10 * 1000" and "&ten_thousand"
limits.

The only potential problem might be a warning about possible
"sign" mismatch from the compiler. But I do not see any
even with make W=2.

Best Regards,
Petr