linux-kernel - Re: [PATCH 1/3] hexdump: more output formatting

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Date:	Wed, 30 May 2007 15:25:31 -0700
From:	Randy Dunlap <randy.dunlap@...cle.com>
To:	Satyam Sharma <satyam.sharma@...il.com>
CC:	Christoph Lameter <clameter@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, hugh@...itas.com
Subject: Re: [PATCH 1/3] hexdump: more output formatting

Satyam Sharma wrote:
> On 5/31/07, Randy Dunlap <randy.dunlap@...cle.com> wrote:
>> Satyam Sharma wrote:
>> > Hello Randy,
>> >
>> >> Add a prefix string parameter.  Callers are responsible for any
>> >> string length/alignment that they want to see in the output.  I.e.,
>> >> callers should pad strings to achieve alignment if they want that.
>> >>
>> >> Add rowsize parameter.  This is the number of raw data bytes
>> >> to be printed per line.  Must be 16 or 32.
>> >>
>> >> Add a group_size parameter.  This allows callers to dump values
>> >> as 1-byte, 2-byte, 4-byte, or 8-byte numbers.  Default is
>> >> 1-byte numbers.  If the total length is not an even multiple
>> >> of group_size, 1-byte numbers are printed.
>> >
>> > I wonder if (over-)engineering could hurt its adoption by more kernel
>> > users. There aren't very many 8-argument monsters in the kernel,
>> > and one would expect hexdump() to be easier on the fingers to
>> > type? :-) Why not just continue with reasonable default/fixed rowsize
>> > and groupsize values?
>>
>> Yes, one can try to satisfy the users/callers by adapting to their
>> needs (wishes), which requires parameters or such; or one can have
>> no callers and end up with (around 11 currently) different hex dump
>> functions in the kernel source tree, but no users of lib/hexdump.c.
> 
> Yes, you're right, but I was just wondering whether any users really
> cared enough about the rowsize and groupsize, also seeing that
> accommodating these two args leads to a lot of increase in code.

The only other (just-posted) user is in mm/prio_tree.c (in the -mm
kernel), and it wants non-byte-mode output (pointers, 4 bytes or
8 bytes).  And it just doesn't make much sense to print only
2 pointers per line (when ASCII isn't being printed).

But maybe prio_tree.c::dump_vma() just isn't a good candidate
for lib/hexdump usage...

I need to look at other potential users/callers to see what the
needs are.

>> But it won't take much more "requirements" for me to drop the patch.
> 
> Please, don't drop this! I only complained because when global or
> commonly-used functions have very long arglists, one tends to forget
> which arg goes at which number, and it becomes necessary to write
> the calls with having the prototype simultaneously open in another
> terminal for reference! ...
> 
>> >> Add an "ascii" output parameter.  This causes ASCII data output
>> >> following the hex data output.


-- 
~Randy
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