Re: [PATCH v3 2/3] hexdump: Allow skipping identical lines

[Andy Shevchenko]

On Wed, Mar 19, 2025 at 05:08:11PM +0100, Miquel Raynal wrote:
> When dumping long buffers (especially for debug purposes) it may be very
> convenient to sometimes avoid spitting all the lines of the buffer if
> the lines are identical. Typically on embedded devices, the console
> would be wired to a UART running at 115200 bauds, which makes the dumps
> very (very) slow. In this case, having a flag to avoid printing
> duplicated lines is handy.
> 
> Example of a made up repetitive output:
> 0f 53 63 47 56 55 78 7a aa b7 8c ff ff ff ff ff
> ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> ff ff ff ff ff ff ff ff ff ff ff ff 01 2a 39 eb
> 
> Same but with the flag enabled:
> 0f 53 63 47 56 55 78 7a aa b7 8c ff ff ff ff ff
> ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> *
> ff ff ff ff ff ff ff ff ff ff ff ff 01 2a 39 eb

...

>  For printing small buffers (up to 64 bytes long) as a hex string with a
>  certain separator. For larger buffers consider using
> -:c:func:`print_hex`.

Instead of fixing this (see also comment in previous patch), just add the text
like

:c:func:`print_hex` is  especially useful since duplicated lines can be skipped
automatically to reduce the overhead with the ``DUMP_SKIP_IDENTICAL_LINES`` flag.

> +:c:func:`print_hex`, especially since duplicated lines can be
> +skipped automatically to reduce the overhead with the
> +``DUMP_SKIP_IDENTICAL_LINES`` flag.

Also, can  we also put a sub name spaces to the flags, like for HEX/ASCII

DUMP_DATA_HEX
DUMP_DATA_ASCII

This SKIP  will start a new sub name space.

...

>  #include <linux/errno.h>
>  #include <linux/kernel.h>
>  #include <linux/minmax.h>

> +#include <linux/string.h>
>  #include <linux/export.h>

It's more natural to put it here, with given context it makes more order
(speaking of alphabetical one).

-- 
With Best Regards,
Andy Shevchenko