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Re: iWMMXt Linux EABI cross toolchain


Steven Newbury said the following on 03/03/2006 11:50 AM:
--- Khem Raj <khem@mvista.com> wrote:

Steven Newbury said the following on 03/03/2006 02:33 AM:
--- Mike Frysinger <vapier@gentoo.org> wrote:

On Thursday 02 March 2006 23:59, Steven Newbury wrote:
--- Mike Frysinger <vapier@gentoo.org> wrote:
On Thursday 02 March 2006 23:15, Steven Newbury wrote:
OK I think I might have solved this. The toolchain.eclass script was
enabling all languages when the glibc headers are present rather than
when glibc has been built. When the configure script detects that c++
is a selected language it adds -shared-libgcc to the xgcc CFLAGS!
err, what ? toolchain.eclass ? you're using Gentoo ?
Yes! I'm using gentoo! :-) I have now got cross-gcc compiled with threads
so I should be able to build glibc (nptlonly) now fingers crossed.. I
couldn't get it to build without threads. Hopefully I'll have more luck
now..
well you should have said so in the first place, i would have probably
paid a
bit more attention as to what's going on

how are you installing your cross-compiler ? did you use crossdev or are
you
emerging stuff by yourself ? arm/nptl doesnt exist in any of the current Gentoo glibc ebuilds and i dont really plan on backporting anything ...
That's no problem, I've created an overlay and using CVS HEAD
binutils/gcc/glibc.  AFAIK it's the only place with everything in.  I'm
emerging it all myself.


Seems glibc doesn't want to enable nptl for plain arm-* which it has
wrongly
determined I'm using... I am using --with-cpu=iwmmxt --with-arch=iwmmxt
--with-abi=iwmmxt, it is of armv5e compatible.
you should remove --with-abi=iwmmxt if you want a full EABI toolchain. this option enables IWMMXT EABI which is somewhere inbetween EABI and good old ARM ATPCS in addition you should select target as one of arm-*-*-*eabi target in order to let configury know that you want an

I am using arm-iwmmxt-linux-gnueabi, iwmmxt I am using in my gentoo ebuild scripts to select the iwmmxt "--with-*" options etc.

There seems to be some disagreement on what the iWMMXt ABI is, I discussed this
on gnu@gcc.gnu.org:

--- Paul Brook <paul@codesourcery.com> wrote:

On Wednesday 01 March 2006 05:05, Daniel Jacobowitz wrote:
On Wed, Mar 01, 2006 at 04:57:03AM +0000, Steven Newbury wrote:
Thanks for the quick response!
I'm sure it seems I like to make hard wok for myself! It gets worse, I'm
porting Gentoo Linux to iWMMXt with pure EABI kernel and userspace. I'm
not concerned about being able to run old binaries. So is using
abi=iwmmxt really not what I want? A really bad idea?
Absolutely. You want the AAPCS, not Intel's pre-AAPCS ABI.
Actually, -mabi=iwmmxt is AAPCS based. It's diffferent from the old intel iwmmxt ABI.

Having said that, it probably hasn't been tested particularly well, and I wouldn't advise using it unless you really need it (ie. you know you have performace sensitive code that makes extensive use of iWMMXt vector types in function arguments).

So is it just that the iWMMXt ABI is incomplete for EABI or untested or
something else?
As evidents from Paul's IWMMXt ABI is kind of intermediate thing which got started in same direction to refine ABI requirements but then was converted into a more detailed work to define ARM EABI therefore EABI is complete so I would suggest youto use EABI instead.

Steve




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