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From: "H. Peter Anvin" <hpa@zytor.com>
To: Andres Salomon <dilinger@queued.net>
Cc: michael@ellerman.id.au, Ingo Molnar <mingo@elte.hu>,
	devicetree-discuss@lists.ozlabs.org,
	linux-kernel@vger.kernel.org, Milton Miller <miltonm@bga.com>,
	Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v2)
Date: Thu, 18 Nov 2010 09:48:59 -0800	[thread overview]
Message-ID: <4CE5670B.1060300@zytor.com> (raw)
In-Reply-To: <20101118094153.4515cbc2@queued.net>

On 11/18/2010 09:41 AM, Andres Salomon wrote:
>>
>> No, sorry, this sounds like a personal preference that is well out of
>> line with the vast majority of C programmers I've ever come across,
>> not just in the Linux kernel world but outside of it.
> 
> 
> This is actually one of the reasons I specifically like initialized
> static variables (inside of functions).  Take the following code:
> 
> int foo(void)
> {
> 	static char *frob = NULL;
> 	int p;
> 
> 	if (frob) {
> 		...
> 	}
> 
> 
> Upon seeing that and thinking "whoa, how could frob be
> initialized and then checked?", I realize that it's either a bug or I
> look back at the initialization and realize that frob is static.  It's
> less obvious (to me) with non-explicit initialization.

I have to agree with this one.  In general I dislike relying on an
implicit (even well-defined) initialized value; unfortunately we ripped
out explicit initializations across the Linux kernel, not due to
readability but due to the fact that long-since-obsolete versions of gcc
would put explicitly-initialized variables in data rather than bss even
if the initial value is zero.

	-hpa


-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.


WARNING: multiple messages have this Message-ID (diff)
From: "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
To: Andres Salomon <dilinger-pFFUokh25LWsTnJN9+BGXg@public.gmane.org>
Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Milton Miller <miltonm-ogEGBHC/i9Y@public.gmane.org>,
	Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>,
	Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Subject: Re: [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v2)
Date: Thu, 18 Nov 2010 09:48:59 -0800	[thread overview]
Message-ID: <4CE5670B.1060300@zytor.com> (raw)
In-Reply-To: <20101118094153.4515cbc2-pFFUokh25LWsTnJN9+BGXg@public.gmane.org>

On 11/18/2010 09:41 AM, Andres Salomon wrote:
>>
>> No, sorry, this sounds like a personal preference that is well out of
>> line with the vast majority of C programmers I've ever come across,
>> not just in the Linux kernel world but outside of it.
> 
> 
> This is actually one of the reasons I specifically like initialized
> static variables (inside of functions).  Take the following code:
> 
> int foo(void)
> {
> 	static char *frob = NULL;
> 	int p;
> 
> 	if (frob) {
> 		...
> 	}
> 
> 
> Upon seeing that and thinking "whoa, how could frob be
> initialized and then checked?", I realize that it's either a bug or I
> look back at the initialization and realize that frob is static.  It's
> less obvious (to me) with non-explicit initialization.

I have to agree with this one.  In general I dislike relying on an
implicit (even well-defined) initialized value; unfortunately we ripped
out explicit initializations across the Linux kernel, not due to
readability but due to the fact that long-since-obsolete versions of gcc
would put explicitly-initialized variables in data rather than bss even
if the initial value is zero.

	-hpa


-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

  reply	other threads:[~2010-11-18 17:50 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-12  5:45 [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v2) Andres Salomon
2010-11-12  5:45 ` Andres Salomon
2010-11-12  7:48 ` Milton Miller
2010-11-12  7:48   ` Milton Miller
2010-11-12  8:27   ` Andres Salomon
2010-11-12  8:27     ` Andres Salomon
2010-11-14  9:50     ` Ingo Molnar
2010-11-15  4:21       ` H. Peter Anvin
2010-11-15  4:21         ` H. Peter Anvin
2010-11-15  7:02         ` Ingo Molnar
2010-11-15  7:02           ` Ingo Molnar
2010-11-15 17:43           ` H. Peter Anvin
2010-11-15 17:43             ` H. Peter Anvin
2010-11-17  6:12             ` [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v3) Andres Salomon
2010-11-17  6:12               ` Andres Salomon
2010-11-29 23:39               ` [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v4) Andres Salomon
2010-12-16  2:58                 ` [tip:x86/olpc] x86, olpc: Speed up device tree creation during boot tip-bot for Andres Salomon
2010-11-18  8:34             ` [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v2) Ingo Molnar
2010-11-18  8:34               ` Ingo Molnar
2010-11-18 11:02               ` Michael Ellerman
2010-11-18 11:02                 ` Michael Ellerman
2010-11-18 15:04                 ` H. Peter Anvin
2010-11-18 15:04                   ` H. Peter Anvin
2010-11-18 17:41                   ` Andres Salomon
2010-11-18 17:41                     ` Andres Salomon
2010-11-18 17:48                     ` H. Peter Anvin [this message]
2010-11-18 17:48                       ` H. Peter Anvin
2010-11-19 20:24                       ` Andres Salomon
2010-11-19 20:24                         ` Andres Salomon
2010-12-23 11:57               ` Ingo Molnar

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