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SubjectRe: [PATCH 2/4] printk: Add ability to set loglevel via "console=" cmdline
On Fri 2019-03-01 16:48:18, Calvin Owens wrote:
> This extends the "console=" interface to allow setting the per-console
> loglevel by adding "/N" to the string, where N is the desired loglevel
> expressed as a base 10 integer. Invalid values are silently ignored.
>
> Signed-off-by: Calvin Owens <calvinowens@fb.com>
> ---
> .../admin-guide/kernel-parameters.txt | 6 ++--
> kernel/printk/console_cmdline.h | 1 +
> kernel/printk/printk.c | 30 +++++++++++++++----
> 3 files changed, 28 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 858b6c0b9a15..afada61dcbce 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -612,10 +612,10 @@
> ttyS<n>[,options]
> ttyUSB0[,options]
> Use the specified serial port. The options are of
> - the form "bbbbpnf", where "bbbb" is the baud rate,
> + the form "bbbbpnf/l", where "bbbb" is the baud rate,
> "p" is parity ("n", "o", or "e"), "n" is number of
> - bits, and "f" is flow control ("r" for RTS or
> - omit it). Default is "9600n8".
> + bits, "f" is flow control ("r" for RTS or omit it),
> + and "l" is the loglevel on [0,7]. Default is "9600n8".

We should a more detailed explanation about the loglevel semantic. It
is either minimal loglevel. Or that it overrides the global
console_loglevel if you accept my proposal.

>
> See Documentation/admin-guide/serial-console.rst for more
> information. See
> diff --git a/kernel/printk/console_cmdline.h b/kernel/printk/console_cmdline.h
> index 11f19c466af5..fbf9b539366e 100644
> --- a/kernel/printk/console_cmdline.h
> +++ b/kernel/printk/console_cmdline.h
> @@ -6,6 +6,7 @@ struct console_cmdline
> {
> char name[16]; /* Name of the driver */
> int index; /* Minor dev. to use */
> + int loglevel; /* Loglevel to use */

The comment will be true only with the new proposal.

> char *options; /* Options for the driver */
> #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
> char *brl_options; /* Options for braille driver */
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 6ead14f8c2bc..2e0eb89f046c 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2104,8 +2105,8 @@ __setup("console_msg_format=", console_msg_format_setup);
> static int __init console_setup(char *str)
> {
> char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */
> - char *s, *options, *brl_options = NULL;
> - int idx;
> + char *s, *options, *llevel, *brl_options = NULL;
> + int idx, loglevel = LOGLEVEL_EMERG;
>
> if (_braille_console_setup(&str, &brl_options))
> return 1;
> @@ -2123,6 +2124,14 @@ static int __init console_setup(char *str)
> options = strchr(str, ',');
> if (options)
> *(options++) = 0;
> +
> + llevel = strchr(str, '/');

This should be:

if (options)
llevel = strchr(options, '/');

> + if (llevel) {
> + *(llevel++) = 0;
> + if (kstrtoint(llevel, 10, &loglevel))
> + loglevel = LOGLEVEL_EMERG;
> + }
> +
> #ifdef __sparc__
> if (!strcmp(str, "ttya"))
> strcpy(buf, "ttyS0");

Best Regards,
Petr

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