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Message from discussion removing bcopy... because it's half broken
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Adrian Bunk  
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 More options Jan 10 2005, 4:00 am
Newsgroups: fa.linux.kernel
From: Adrian Bunk <b...@stusta.de>
Date: Mon, 10 Jan 2005 09:00:09 GMT
Local: Mon, Jan 10 2005 4:00 am
Subject: Re: removing bcopy... because it's half broken
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On Sun, Jan 09, 2005 at 12:19:09PM -0800, Linus Torvalds wrote:

> On Sun, 9 Jan 2005, Arjan van de Ven wrote:

> > Instead of fixing this inconsistency, I decided to remove it entirely,
> > explicit memcpy() and memmove() are prefered anyway (welcome to the 1990's)
> > and nothing in the kernel is using these functions, so this saves code size
> > as well for everyone.

> The problem is that at least some gcc versions would historically generate
> calls to "bcopy" on alpha for structure assignments. Maybe it doesn't any
> more, and no such old gcc versions exist any more, but who knows?
>...

include/asm-alpha/string.h says:

  /*
   * GCC of any recent vintage doesn't do stupid things with bcopy.
   * EGCS 1.1 knows all about expanding memcpy inline, others don't.
   *
   * Similarly for a memset with data = 0.
   */

And Arjan's patch is pretty low-risk:

If it breaks on any architecture with any supported compiler (>= 2.95),
it will break at compile time and there will pretty fast be reports of
this breakage in which case it would be easy to revert his patch.

>            Linus

cu
Adrian

--

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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