Re: [PATCH v3 6/6] Documentation/kernel-parameters: add/update printk_delay/boot_delay

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The documentation for the newly added `printk_delay=` parameter incorrectly advises users that they can specify `lpj=` to calibrate the early boot delay. However, `printk_delay=` is an `early_param` while `lpj=` is processed later during `__setup`, meaning `lpj=` is always ignored for early boot delays.
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--- Patch [6]: [PATCH v3 6/6] Documentation/kernel-parameters: add/update printk_delay/boot_delay ---
commit 1f87f2eec164de9ec5ebb73bcbae241eb291ecf2
Author: Andrew Murray <[email protected]>

Documentation/kernel-parameters: add/update printk_delay/boot_delay

This commit updates the kernel-parameters documentation to reflect the
addition of printk_delay and the deprecation of boot_delay.

> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt

[ ... ]

> @@ -5468,6 +5476,19 @@ Kernel parameters
>  	printk.time=	Show timing data prefixed to each printk message line
>  			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
>  
> +	printk_delay=	[KNL,EARLY]
> +			Milliseconds to delay each printk during and post boot.
> +			Boot time delays only work if GENERIC_CALIBRATE_DELAY
> +			is enabled.
> +
> +			Once booted the delay can be removed or adjusted via
> +			the printk_delay sysctl.
> +
> +			Please note that you may also have to specify "lpj=".

[Severity: Low]
Does "lpj=" actually work for early boot delays? 

Since printk_delay= is registered as an early_param and lpj= is registered
via __setup in init/calibrate.c:lpj_setup(), lpj= is processed after early
parameters.

This means preset_lpj will always be 0 when kernel/printk/printk.c:
printk_delay_setup() calls printk_delay_calculate() during early boot,
causing it to silently ignore the provided lpj= value.

> +			printk_delay values larger than 10 seconds (10000) are
> +			assumed erroneous and ignored.
> +			Format: integer
> +

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Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=6