[PATCH 8/8] cmd: config: allow simple filtering of output

[Rasmus Villemoes]

On Thu, Jul 02 2026, "Simon Glass" <sjg at chromium.org> wrote:

> Hi Rasmus,
>
> On 2026-07-01T17:15:27, Rasmus Villemoes <rv at rasmusvillemoes.dk> wrote:
>> cmd: config: allow simple filtering of output
>>
>> When doing development, it can be quite useful to enable
>> CONFIG_CMD_CONFIG, so that one can always check whether a config knob
>> one has just enabled has actually made it to target.
>>
>> Because sometimes, one doesn't flash the right binary, or maybe one
>> has just done CONFIG_FOO=y in some config fragment, but that had no
>> effect because one would also have to do CONFIG_BAR=y.
>>
>> However, 2400+ lines of text are rather hard to read through. One
>> probably uses a terminal emulator with capturing enabled, but
>> searching back through the capture file is a little tedious, and one
>> easily ends up finding something that doesn't pertain to the most
>> recent 'config' command invocation.
>>
>> So make it possible to limit the output to those lines containing a
>> given string. Like the search functionality in menuconfig, make it
>> case insensitive, because it is much more convenient to type "config
>> pinctrl" than "config PINCTRL".
>> [...]
>>
>> cmd/config.c | 25 ++++++++++++++++++++++---
>>  1 file changed, 22 insertions(+), 3 deletions(-)
>
>> diff --git a/cmd/config.c b/cmd/config.c
>> @@ -29,7 +29,23 @@ static int do_config(struct cmd_tbl *cmdtp, int flag, int argc,
>> +             while (b < e) {
>> +                     n = strchrnul(b, '\n');
>> +                     *n = '\0';
>> +
>> +                     if (strcasestr(b, s)) {
>> +                             puts(b);
>> +                             puts('\n');
>> +                     }
>> +                     b = n + 1;
>> +             }
>
> The two puts() could be a single printf("%s\n", b). 

Well, originally I just had the first puts(), then I found out that our
puts() is not standards-compliant (which would automatically add that
newline). I think I prefer keeping these as-is, to avoid a pathological
case of some .config line exceeding CONFIG_SYS_PBSIZE and then be
truncated (that could happen with some of the config options that are
potentially long lists of strings, OF_LIST, DEVICE_TREE_INCLUDES, the like).

> Also please add an explicit #include <linux/string.h> now that we rely
> on strchrnul() and strcasestr() here.

Ack.

> Reviewed-by: Simon Glass <sjg at chromium.org>
>
> In addition to Tom's comment, how about a simple sandbox test?

Ack.

Rasmus