[PATCH v2] printk: Document that CONFIG_BOOT_PRINTK_DELAY required for boot_delay=

[PATCH v2] printk: Document that CONFIG_BOOT_PRINTK_DELAY required for boot_delay=

[Bjorn Helgaas]

From: Bjorn Helgaas <bhelgaas@google.com>

Document the fact that CONFIG_BOOT_PRINTK_DELAY must be enabled for the
"boot_delay" kernel parameter to work.  Also mention that "lpj=" may be
necessary.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
Changes from v1 (https://lore.kernel.org/all/20230123180440.901793-1-helgaas@kernel.org/):
- Clarify use of "lpj=".  Reword consequences of delay larger than 10000.

 Documentation/admin-guide/kernel-parameters.txt | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 6cfa6e3996cf..814e58487239 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -480,8 +480,10 @@
 			See Documentation/block/cmdline-partition.rst
 
 	boot_delay=	Milliseconds to delay each printk during boot.
-			Values larger than 10 seconds (10000) are changed to
-			no delay (0).
+			Only works if CONFIG_BOOT_PRINTK_DELAY is enabled,
+			and you may also have to specify "lpj=".  Boot_delay
+			values larger than 10 seconds (10000) are assumed
+			erroneous and ignored.
 			Format: integer
 
 	bootconfig	[KNL]
-- 
2.25.1

Re: [PATCH v2] printk: Document that CONFIG_BOOT_PRINTK_DELAY required for boot_delay=

[Randy Dunlap]

On 1/26/23 14:54, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@google.com>
> 
> Document the fact that CONFIG_BOOT_PRINTK_DELAY must be enabled for the
> "boot_delay" kernel parameter to work.  Also mention that "lpj=" may be
> necessary.
> 
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Reviewed-by: Randy Dunlap <rdunlap@infradead.org>

Thanks.

> ---
> Changes from v1 (https://lore.kernel.org/all/20230123180440.901793-1-helgaas@kernel.org/):
> - Clarify use of "lpj=".  Reword consequences of delay larger than 10000.
> 
>  Documentation/admin-guide/kernel-parameters.txt | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 6cfa6e3996cf..814e58487239 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -480,8 +480,10 @@
>  			See Documentation/block/cmdline-partition.rst
>  
>  	boot_delay=	Milliseconds to delay each printk during boot.
> -			Values larger than 10 seconds (10000) are changed to
> -			no delay (0).
> +			Only works if CONFIG_BOOT_PRINTK_DELAY is enabled,
> +			and you may also have to specify "lpj=".  Boot_delay
> +			values larger than 10 seconds (10000) are assumed
> +			erroneous and ignored.
>  			Format: integer
>  
>  	bootconfig	[KNL]

-- 
~Randy

Re: [PATCH v2] printk: Document that CONFIG_BOOT_PRINTK_DELAY required for boot_delay=

[Jonathan Corbet]

Bjorn Helgaas <helgaas@kernel.org> writes:

> From: Bjorn Helgaas <bhelgaas@google.com>
>
> Document the fact that CONFIG_BOOT_PRINTK_DELAY must be enabled for the
> "boot_delay" kernel parameter to work.  Also mention that "lpj=" may be
> necessary.
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
> Changes from v1 (https://lore.kernel.org/all/20230123180440.901793-1-helgaas@kernel.org/):
> - Clarify use of "lpj=".  Reword consequences of delay larger than 10000.
>
>  Documentation/admin-guide/kernel-parameters.txt | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 6cfa6e3996cf..814e58487239 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -480,8 +480,10 @@
>  			See Documentation/block/cmdline-partition.rst
>  
>  	boot_delay=	Milliseconds to delay each printk during boot.
> -			Values larger than 10 seconds (10000) are changed to
> -			no delay (0).
> +			Only works if CONFIG_BOOT_PRINTK_DELAY is enabled,
> +			and you may also have to specify "lpj=".  Boot_delay
> +			values larger than 10 seconds (10000) are assumed
> +			erroneous and ignored.
>  			Format: integer

Applied, thanks.

jon