linux-kernel - Re: [PATCH 0/2] hexdump: Allow skipping identical lines

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Message-ID: <20240827110147.29a7481a@xps-13>
Date: Tue, 27 Aug 2024 11:01:47 +0200
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Petr Mladek <pmladek@...e.com>, Steven Rostedt <rostedt@...dmis.org>,
 Rasmus Villemoes <linux@...musvillemoes.dk>, Sergey Senozhatsky
 <senozhatsky@...omium.org>, Jonathan Corbet <corbet@....net>, John Ogness
 <john.ogness@...utronix.de>, Andrew Morton <akpm@...ux-foundation.org>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] hexdump: Allow skipping identical lines

Hi Andy,

Thanks for your feedback.

andriy.shevchenko@...ux.intel.com wrote on Mon, 26 Aug 2024 20:32:20
+0300:

> On Mon, Aug 26, 2024 at 06:24:14PM +0200, Miquel Raynal wrote:
> > Hello!
> > 
> > While working on NAND issues, I used print_hex_dump() a lot to compare
> > data. But I am mostly working on embedded systems where the kernel
> > messages go through a serial console. Sometimes network support is an
> > option, sometimes not. Anyway, I often print buffers both in kernel
> > space and user space to compare them, and they may be full of 0's or
> > 1's, which means lines are repeated a lot in the output and this is slow
> > *and* hard to compare.
> > 
> > I initially hacked into lib/hexdump.c for my own purpose and just
> > discarded all the other users, but it felt like this might be a useful
> > feature for others and decided to make it a public patch.
> > 
> > * First patch changes the "ascii" parameter into a "flags" variable now
> >   accepting the value: DUMP_FLAG_ASCII.
> > * Second patch adds a new flag to skip the identical lines, because this
> >   must be an opt-in parameter, I guess.  
> 
> This is quite a long to look into, can you please add a summary here which
> includes (but not limited to) the following:
> 1) examples before and after (ah, I see you have that in the patch 2,
>    but would be still good to have in the cover letter);

No problem, I can make this part of the cover letter as well.

> 2) excerpts of the code for before and after (since the type of the ascii
>    parameter had been changed).

In patch 1/2 there is the Coccinelle script, but I must admit the
syntax is not super clear, so I will improve this by showing the two
main user cases with a proper human-readable diff.

> Also here is the formal NAK till the series gains the test cases.

What test cases are you talking about?

Thanks,
Miquèl