linux-kernel - Re: Use of '%#02x' is almost always wrong

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Message-ID: <9bae5c76-db1e-b9e3-cdfa-ab22f9d8b58c@petrovitsch.priv.at>
Date:   Thu, 14 Oct 2021 01:16:04 +0200
From:   Bernd Petrovitsch <bernd@...rovitsch.priv.at>
To:     David Laight <David.Laight@...LAB.COM>,
        "'Joe Perches'" <joe@...ches.com>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     kernel-janitors <kernel-janitors@...r.kernel.org>
Subject: Re: Use of '%#02x' is almost always wrong

Hi all!

On 12/10/2021 23:10, David Laight wrote:
[...]
>> So presumably all the uses of %#02x in the kernel are not outputting
>> what is actually expected.  Perhaps all of these should use %#04x.
> 
> Doesn't help. The definition of "%#x" is completely broken.

Seconded ...

> Basically 0 doesn't get the "0x" prefix, so "%#04x" outputs

... just because of that.
And if one get's in touch with tools where format strings are
the % -stuff is not consistently used ...

> "0000" if the value is zero.
> So the correct replacement is (probably) "0x%02x".

At least it's consistent that way.

And in the big techie picture, I don't see what the '#' modifer
buys and why it makes sense to use it.

Kind regards,
	Bernd
-- 
Bernd Petrovitsch                  Email : bernd@...rovitsch.priv.at
      There is NO CLOUD, just other people's computers. - FSFE
                      LUGA : http://www.luga.at