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From: Adrian Bunk <bunk@fs.tum.de>
To: Mikael Pettersson <mikpe@csd.uu.se>, Thomas Hood <jdthood@mail.com>
Cc: linux-kernel@vger.kernel.org
Subject: remove __ALIGN from pnpbios/bioscalls.c?
Date: Mon, 15 Sep 2003 08:09:42 +0200	[thread overview]
Message-ID: <20030915060941.GA126@fs.tum.de> (raw)
In-Reply-To: <200309131104.h8DB4WqV021726@harpo.it.uu.se>

On Sat, Sep 13, 2003 at 01:04:32PM +0200, Mikael Pettersson wrote:
> On Sat, 13 Sep 2003 00:51:39 +0200, Adrian Bunk <bunk@fs.tum.de> wrote:
> >> > > - Which CPUs exactly need X86_ALIGNMENT_16?
> >> >
> >> >Unsure. This could use testing on a few systems.
> >> 
> >> K7s and P5s (and 486s too if I remember correctly) strongly prefer
> >> code entry points and loop labels to be 16-byte aligned. This is
> >> due to the way code is fetched from L1.
> >>...
> >
> >Hm, that's pretty different from the definition in -test5:
> >
> >config X86_ALIGNMENT_16
> >        bool
> >        depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || 
> >          MELAN || MK6 || M586MMX || M586TSC || M586 || M486 || MVIAC3_2
> >        default y
> 
> My comment referred to data from Intel and AMD code optimisation
> guides.
> 
> The kernel only uses X86_ALIGNMENT_16 to derive two __ALIGN macros
> for assembly code, but it doesn't use them except in one place in
> the pnpbios code.

It seems thoe only architecture really using the __ALIGN macros is m68k. 
This is irrelevant in this case since X86_ALIGNMENT_16 only affects 
i386.

> gcc -march=<cpu type> should generate appropriate alignment for
> function entries and loop labels.
> 
> I suspect X86_ALIGNMENT_16 is a left-over from old code.
> Perhaps its time to retire it.

Thomas, what exactly do you need __ALIGN_STR in the function 
pnp_bios_callfunc in drivers/pnp/pnpbios/bioscalls.c for?

> /Mikael

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


      reply	other threads:[~2003-09-15  6:09 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-09-13 11:04 RFC: [2.6 patch] better i386 CPU selection Mikael Pettersson
2003-09-15  6:09 ` Adrian Bunk [this message]

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