linux-kernel - Re: X32 psABI status update

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Message-ID: <AANLkTikWyEzxDsjAEcR71fth+558qEA6HZ0PX64V+V0v@mail.gmail.com>
Date:	Thu, 17 Mar 2011 07:43:50 -0700
From:	"H.J. Lu" <hjl.tools@...il.com>
To:	Mike Frysinger <vapier@...too.org>
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 Wed, Mar 16, 2011 at 10:45 PM, Mike Frysinger <vapier@...too.org> wrote:
> 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.

I will take a look.

>> > 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.

If you can show me some real examples how __x32__ will be used, I will
take a look.

Thanks.

-- 
H.J.
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