linux-kernel - Re: [PATCH] x86: PIC, L-APIC and I/O APIC debug information

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Message-ID: <18564.38760.212333.375520@harpo.it.uu.se>
Date:	Mon, 21 Jul 2008 16:04:24 +0200
From:	Mikael Pettersson <mikpe@...uu.se>
To:	"Maciej W. Rozycki" <macro@...ux-mips.org>
Cc:	Mikael Pettersson <mikpe@...uu.se>, Ingo Molnar <mingo@...e.hu>,
	Chuck Ebbert <cebbert@...hat.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: PIC, L-APIC and I/O APIC debug information

Maciej W. Rozycki writes:
 > On Mon, 21 Jul 2008, Mikael Pettersson wrote:
 > 
 > >  > +#define __apicdebuginit(type) static type __init
 > > ...
 > >  > -void __init print_IO_APIC(void)
 > >  > +
 > >  > +__apicdebuginit(void) print_IO_APIC(void)
 > >  >  {
 > > 
 > > I _really_ dislike how this abuses the C macro preprocessor
 > > to create pointless new syntax.
 > > 
 > > Since you're editing these function definitions anyway why
 > > not just spell out "static void __init" in readable proper C?
 > 
 >  This is so that while debugging you can make all these functions global
 > with a single change in one place, rather than going through the whole
 > file and finding all the relevant function headers.  Presumably the
 > original reason for the existence of the macro.  Unfortunately an
 > object-like macro cannot be used here, as the "static" keyword has to come
 > first in a function declaration and the section attribute has to come
 > after the type designation.
 > 
 >  What's wrong with the syntax in your opinion?

It's not even remotely C-like, which will cause confusion
for anyone or anything trying to read and understand the code.

(Basically you're on the path to PL/1 or Bourne C, neither of
which were great from a software engineering point of view.)

Something like the following looks saner to me, would it work for you?

	#ifdef debug
	#define apicdebug	/* empty */
	#define __apicinit	/* empty */
	#else
	#define apicdebug	static
	#define __apicinit	__init
	#endif
	...
	apicdebug void __apicinit print_IO_APIC(void)
	{ .. }

/Mikael
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