linux-kernel - Re: X32 psABI status update

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Message-Id: <201103170145.46326.vapier@gentoo.org>
Date:	Thu, 17 Mar 2011 01:45:45 -0400
From:	Mike Frysinger <vapier@...too.org>
To:	"H.J. Lu" <hjl.tools@...il.com>
Cc:	libc-alpha@...rceware.org, GCC Development <gcc@....gnu.org>,
	LKML <linux-kernel@...r.kernel.org>, x32-abi@...glegroups.com
Subject: Re: X32 psABI status update

On Thursday, March 17, 2011 01:21:16 H.J. Lu wrote:
> On Wed, Mar 16, 2011 at 7:57 PM, Mike Frysinger <vapier@...too.org> wrote:
> > ok, took long enough, but that answers most things.  your usage of "x32-"
> > prefixed binaries in the documentation seems to imply a lot more than the
> > fact you just picked those locally to avoid system collisions.  this
> > isnt a wiki page, otherwise i'd clean things up for you.
> 
> Any suggestion how to create a wiki page for x32?

seems like the sites.google.com documentation says it includes wiki support.
	http://sites.google.com/site/projectwikitemplate_en/

ive never used google sites before, so i dont know how to actually enable it 
on the admin side of things.

> > in looking at the gcc files, it doesnt seem like there's any defines
> > setup to declare x32 directly.  instead, you'd have to do something
> > like: #ifdef __x86_64__
> > # if __SIZEOF_LONG__ == 8
> > /* x86_64 */
> > # else
> > /* x32 */
> > # endif
> > #endif
> > 
> > any plans on adding an __x32__ (or whatever) cpp symbol to keep people
> > from coming up with their own special/broken crap ?  or are there some
> > already that i'm not seeing ?
> 
> The idea is in most cases, you only need to check __x86_64__ since x32 and
> x86-64 are very close.  In some cases, x32 is very different from x86_64,
> like assembly codes on long and pointer, you can check __x86_64__ and
> __LP64__. In glibc, I used a different approach by using macros REG_RAX,
> .., MOV_LP, ADD_LP, SUB_LP and CMP_LP in assembly codes.

arm/mips/ppc sets up explicit ABI defines to clearly differentiate between 
things.  while __LP64__ should work here, it seems like a poor substitute.  
how about builtin_define("__X32__") ?  or __ABI_X32__ ?  doesnt seem like i386 
has a standard in this regard to piggy off of.
-mike

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