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Subject: Re: [PATCH v2] vsprintf: introduce %dE for error constants
To:     Petr Mladek <pmladek@suse.com>,
        =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= <uwe@kleine-koenig.org>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Jonathan Corbet <corbet@lwn.net>,
        metux IT consult Enrico Weigelt <lkml@metux.net>,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
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 <74303921-aa95-9962-2254-27e556af54f4@kleine-koenig.org>
 <20190829081249.3zvvsa4ggb5pfozl@pathway.suse.cz>
From:   Rasmus Villemoes <linux@rasmusvillemoes.dk>
Message-ID: <39eda8f7-8c39-f899-075f-b4abdefe0098@rasmusvillemoes.dk>
Date:   Thu, 29 Aug 2019 11:00:58 +0200
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On 29/08/2019 10.12, Petr Mladek wrote:
> On Wed 2019-08-28 21:18:37, Uwe Kleine-K?nig  wrote:

> BTW: I though more about generating or cut&pasting the arrary.
> I can't find any reasonable way how to generate it.

Something like this seems to work, though it probably needs some massage
to be accepted by kbuild folks:

define filechk_errcode.h
	echo '#include <linux/errno.h>' | \
	$(CPP) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) -dM - | \
	grep 'define E' | sort -k3,3n | \
	awk '{print "errcode("$$2")\t/* "$$3" */"}'
endef

include/generated/errcode.h: FORCE
	$(call filechk,errcode.h)

Then one can just #define errcode(foo) ... right before #include
<generated/errcode.h>. It cannot be used to generate cases in a switch()
because some expand to the same number, but that's ok, because I can't
imagine the switch actually generating good or small code. I haven't
checked how or whether it works in a cross-compile situation.

Rasmus