new triplet for x32 psABI?

new triplet for x32 psABI?

[Michael LIAO]

Sorry, resend with plain text format.

Hi, Everyone

As x32 psABI (https://sites.google.com/site/x32abi/) is invented, do
we need a new triplet for system relies on triplet to figure out it's
targeted on x32 environment. The new triplet would look like
'x86_64-unknown-linux-gnux32' for x32 vs 'x86_64-unknown-linux-gnu'
for regular 64-bit. This's similar to EABI added to ARM or PowerPC,
where 'arm-unknown-linux-gnueabi' vs. 'arm-unknown-linux-gnu'.

The new triple doesn't introduce a new target (still x86_64) but just
a new environment 'gnux32' to specify x32 ABI is used for code
generation.

The current scheme documented on website
(https://sites.google.com/site/x32abi/) uses the existing triplet but
specify x32 ABI through compiler/linker options. It works for most
compilers aware of that, but how other tools not handling
compiler/linker options knows the current build is targeted on a
different environment?

Any comments or alternative suggestion?

Yours
- Michael

Re: new triplet for x32 psABI?

[Eric Blake]

On 10/03/2011 04:25 PM, Michael LIAO wrote:
> Sorry, resend with plain text format.
>
> Hi, Everyone
>
> As x32 psABI (https://sites.google.com/site/x32abi/) is invented, do
> we need a new triplet for system relies on triplet to figure out it's
> targeted on x32 environment. The new triplet would look like
> 'x86_64-unknown-linux-gnux32' for x32 vs 'x86_64-unknown-linux-gnu'
> for regular 64-bit. This's similar to EABI added to ARM or PowerPC,
> where 'arm-unknown-linux-gnueabi' vs. 'arm-unknown-linux-gnu'.

Discussions on new triplets are worthless on the autoconf list, which is 
only a downstream consumer of config.guess; rather, your questions 
should be directed to config-patches@gnu.org [added to cc].

>
> The new triple doesn't introduce a new target (still x86_64) but just
> a new environment 'gnux32' to specify x32 ABI is used for code
> generation.
>
> The current scheme documented on website
> (https://sites.google.com/site/x32abi/) uses the existing triplet but
> specify x32 ABI through compiler/linker options. It works for most
> compilers aware of that, but how other tools not handling
> compiler/linker options knows the current build is targeted on a
> different environment?
>
> Any comments or alternative suggestion?
>
> Yours
> - Michael
>
-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

Re: new triplet for x32 psABI?

[Mike Frysinger]

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On Monday, October 03, 2011 18:25:46 Michael LIAO wrote:
> As x32 psABI (https://sites.google.com/site/x32abi/) is invented, do
> we need a new triplet for system relies on triplet to figure out it's
> targeted on x32 environment. The new triplet would look like
> 'x86_64-unknown-linux-gnux32' for x32 vs 'x86_64-unknown-linux-gnu'
> for regular 64-bit. This's similar to EABI added to ARM or PowerPC,
> where 'arm-unknown-linux-gnueabi' vs. 'arm-unknown-linux-gnu'.

do you have examples of why you need this ?

> The current scheme documented on website
> (https://sites.google.com/site/x32abi/) uses the existing triplet but
> specify x32 ABI through compiler/linker options. It works for most
> compilers aware of that, but how other tools not handling
> compiler/linker options knows the current build is targeted on a
> different environment?

the mips people have been using a single tuple for multiple abis (n32 and 
n64), and it doesn't appear to have been a blocker for them ...
-mike

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Re: new triplet for x32 psABI?

[Michael LIAO]

Most examples would be related to tools generating code.

Suppose you have a software package with several hard-coded fully
optimized assembly file for different targets. Your build system need
to know the current target as well as target ABI to select the correct
assembly file to build it. It even desirable if it includes a simple
script to help generate assembly code (like the one in OpenSSL), you'd
better know the target ABI to prepare proper glue code without
breaking ABI.

Yours
- Michael

On Mon, Oct 3, 2011 at 3:34 PM, Mike Frysinger <vapier@gentoo.org> wrote:
> On Monday, October 03, 2011 18:25:46 Michael LIAO wrote:
>> As x32 psABI (https://sites.google.com/site/x32abi/) is invented, do
>> we need a new triplet for system relies on triplet to figure out it's
>> targeted on x32 environment. The new triplet would look like
>> 'x86_64-unknown-linux-gnux32' for x32 vs 'x86_64-unknown-linux-gnu'
>> for regular 64-bit. This's similar to EABI added to ARM or PowerPC,
>> where 'arm-unknown-linux-gnueabi' vs. 'arm-unknown-linux-gnu'.
>
> do you have examples of why you need this ?
>
>> The current scheme documented on website
>> (https://sites.google.com/site/x32abi/) uses the existing triplet but
>> specify x32 ABI through compiler/linker options. It works for most
>> compilers aware of that, but how other tools not handling
>> compiler/linker options knows the current build is targeted on a
>> different environment?
>
> the mips people have been using a single tuple for multiple abis (n32 and
> n64), and it doesn't appear to have been a blocker for them ...
> -mike
>

Re: new triplet for x32 psABI?

[Mike Frysinger]

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On Monday, October 03, 2011 18:57:28 Michael LIAO wrote:

please don't top post

> Most examples would be related to tools generating code.
> 
> Suppose you have a software package with several hard-coded fully
> optimized assembly file for different targets. Your build system need
> to know the current target as well as target ABI to select the correct
> assembly file to build it. It even desirable if it includes a simple
> script to help generate assembly code (like the one in OpenSSL), you'd
> better know the target ABI to prepare proper glue code without
> breaking ABI.

hjlu posted examples to the x32 site as to handle this.  the only difference 
between x86_64 and x32 is the size of the pointers.

please explain why his example won't cover the OpenSSL's needs.  (side note; 
OpenSSL is a terrible example to use because (1) they don't even use autoconf 
or any autotools and (2) they don't generally use sane tuples like the config 
project).
-mike

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Re: new triplet for x32 psABI?

[H.J. Lu]

On Mon, Oct 3, 2011 at 3:57 PM, Michael LIAO <michael.hliao@gmail.com> wrote:
> Most examples would be related to tools generating code.
>
> Suppose you have a software package with several hard-coded fully
> optimized assembly file for different targets. Your build system need
> to know the current target as well as target ABI to select the correct
> assembly file to build it. It even desirable if it includes a simple
> script to help generate assembly code (like the one in OpenSSL), you'd
> better know the target ABI to prepare proper glue code without
> breaking ABI.
>

X32 assembly codes are very close to x86-64 ones. In come cases,
they are 100% compatible.

In kernel, x32 vDSO is built from the x86-64 .o files for x86-64 vDSO.
In gmp, you can assemble x86-64 assembly codes directly into x32
object files.  Adding x32 target triplet may not be necessarily helpful.


-- 
H.J.

Re: new triplet for x32 psABI?

[Michael LIAO]

On Mon, Oct 3, 2011 at 4:03 PM, Mike Frysinger <vapier@gentoo.org> wrote:
> On Monday, October 03, 2011 18:57:28 Michael LIAO wrote:
>
> please don't top post
>

sorry, it's my first post on mailing.

>> Most examples would be related to tools generating code.
>>
>> Suppose you have a software package with several hard-coded fully
>> optimized assembly file for different targets. Your build system need
>> to know the current target as well as target ABI to select the correct
>> assembly file to build it. It even desirable if it includes a simple
>> script to help generate assembly code (like the one in OpenSSL), you'd
>> better know the target ABI to prepare proper glue code without
>> breaking ABI.
>
> hjlu posted examples to the x32 site as to handle this.  the only difference
> between x86_64 and x32 is the size of the pointers.
>

Besides the pointer size, there are other differences like indirect
branch which need different code sequence on x32 and x64. Indirect
branch would be used in assembly code (yeah, concrete example would
valuable here but indirect branch should be used potentially and
possibly in assembly code.) If the assembly code use indirect branch,
it needs to know the target ABI and generate/use difference code path.

> please explain why his example won't cover the OpenSSL's needs.  (side note;
> OpenSSL is a terrible example to use because (1) they don't even use autoconf
> or any autotools and (2) they don't generally use sane tuples like the config
> project).
> -mike
>

Openssl may not a good example and I just used as I remembered it uses
assembly code.

Re: new triplet for x32 psABI?

[Mike Frysinger]

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On Monday, October 03, 2011 19:47:57 Michael LIAO wrote:
> On Mon, Oct 3, 2011 at 4:03 PM, Mike Frysinger wrote:
> > On Monday, October 03, 2011 18:57:28 Michael LIAO wrote:
> >> Most examples would be related to tools generating code.
> >> 
> >> Suppose you have a software package with several hard-coded fully
> >> optimized assembly file for different targets. Your build system need
> >> to know the current target as well as target ABI to select the correct
> >> assembly file to build it. It even desirable if it includes a simple
> >> script to help generate assembly code (like the one in OpenSSL), you'd
> >> better know the target ABI to prepare proper glue code without
> >> breaking ABI.
> > 
> > hjlu posted examples to the x32 site as to handle this.  the only
> > difference between x86_64 and x32 is the size of the pointers.
> 
> Besides the pointer size, there are other differences like indirect
> branch which need different code sequence on x32 and x64. Indirect
> branch would be used in assembly code (yeah, concrete example would
> valuable here but indirect branch should be used potentially and
> possibly in assembly code.) If the assembly code use indirect branch,
> it needs to know the target ABI and generate/use difference code path.

in terms of asm code, it's still possible to use ifdef's to handle cases where 
you truly need different code paths.

in terms of a tool that generates code itself (like gcc), i'm not sure a 
different tuple would make it any easier.  gcc itself simply adds an abi 
configure flag to control what it supports since the backend shares a lot more 
code than is unique to each abi.

we have precedence here where multiple abi's work with a single tuple, and it 
hasn't been a significant hindrance for them.  adding a new tuple is also not 
something to be done lightly ... a lot of code out there parses tuples, and 
they would need updating.

not that i'm the one to convince here, it's just that you need real data to 
back up proposals that shows pros/cons and why your suggestion ultimately has 
more pros than cons ;).
-mike

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Re: new triplet for x32 psABI?

[H.J. Lu]

On Mon, Oct 3, 2011 at 4:47 PM, Michael LIAO <michael.hliao@gmail.com> wrote:
> On Mon, Oct 3, 2011 at 4:03 PM, Mike Frysinger <vapier@gentoo.org> wrote:
>> On Monday, October 03, 2011 18:57:28 Michael LIAO wrote:
>>
>> please don't top post
>>
>
> sorry, it's my first post on mailing.
>
>>> Most examples would be related to tools generating code.
>>>
>>> Suppose you have a software package with several hard-coded fully
>>> optimized assembly file for different targets. Your build system need
>>> to know the current target as well as target ABI to select the correct
>>> assembly file to build it. It even desirable if it includes a simple
>>> script to help generate assembly code (like the one in OpenSSL), you'd
>>> better know the target ABI to prepare proper glue code without
>>> breaking ABI.
>>
>> hjlu posted examples to the x32 site as to handle this.  the only difference
>> between x86_64 and x32 is the size of the pointers.
>>
>
> Besides the pointer size, there are other differences like indirect
> branch which need different code sequence on x32 and x64. Indirect
> branch would be used in assembly code (yeah, concrete example would
> valuable here but indirect branch should be used potentially and
> possibly in assembly code.) If the assembly code use indirect branch,
> it needs to know the target ABI and generate/use difference code path.
>

In assembly codes, most, if not all, of x86-64 indirect branch work fine for x32


-- 
H.J.

Re: new triplet for x32 psABI?

[Michael LIAO]

On Mon, Oct 3, 2011 at 5:46 PM, Mike Frysinger <vapier@gentoo.org> wrote:
> On Monday, October 03, 2011 19:47:57 Michael LIAO wrote:
>> On Mon, Oct 3, 2011 at 4:03 PM, Mike Frysinger wrote:
>> > On Monday, October 03, 2011 18:57:28 Michael LIAO wrote:
>> >> Most examples would be related to tools generating code.
>> >>
>> >> Suppose you have a software package with several hard-coded fully
>> >> optimized assembly file for different targets. Your build system need
>> >> to know the current target as well as target ABI to select the correct
>> >> assembly file to build it. It even desirable if it includes a simple
>> >> script to help generate assembly code (like the one in OpenSSL), you'd
>> >> better know the target ABI to prepare proper glue code without
>> >> breaking ABI.
>> >
>> > hjlu posted examples to the x32 site as to handle this.  the only
>> > difference between x86_64 and x32 is the size of the pointers.
>>
>> Besides the pointer size, there are other differences like indirect
>> branch which need different code sequence on x32 and x64. Indirect
>> branch would be used in assembly code (yeah, concrete example would
>> valuable here but indirect branch should be used potentially and
>> possibly in assembly code.) If the assembly code use indirect branch,
>> it needs to know the target ABI and generate/use difference code path.
>
> in terms of asm code, it's still possible to use ifdef's to handle cases where
> you truly need different code paths.

Yeah, we could have '#ifdef X32ABI" in assembly file to select
different path. But, how to generate that macro, says X32ABI, based on
autoconf to detect/select target (not only target architecture but
also target ABI.). A new triplet in general is needed to simplify that
instead of compiler/linker options only or inventing itself by each
software package itself. The reason for a new triplet is to get such
information little canonical, in somewhat.

>
> in terms of a tool that generates code itself (like gcc), i'm not sure a
> different tuple would make it any easier.  gcc itself simply adds an abi
> configure flag to control what it supports since the backend shares a lot more
> code than is unique to each abi.

not all tools like gcc has the chance to specify different ABI through
compiler option. it's especially true for simple tool to generate
code, maybe just at compile time. They may need something directly to
tell which ABI will be used.

>
> we have precedence here where multiple abi's work with a single tuple, and it
> hasn't been a significant hindrance for them.  adding a new tuple is also not
> something to be done lightly ... a lot of code out there parses tuples, and
> they would need updating.

yeah, I totally agree. At first stage, people may still need explicit
specify compiler/linker options '-mx32' to build a non-x32-aware
package with x32 ABI for correctness. But, for package requires to be
x32-aware, it could check triplet.

>
> not that i'm the one to convince here, it's just that you need real data to
> back up proposals that shows pros/cons and why your suggestion ultimately has
> more pros than cons ;).

yeah, that's why mailing list is always CCed, :)

> -mike
>

Re: new triplet for x32 psABI?

[Michael LIAO]

On Mon, Oct 3, 2011 at 5:53 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Mon, Oct 3, 2011 at 4:47 PM, Michael LIAO <michael.hliao@gmail.com> wrote:
>> On Mon, Oct 3, 2011 at 4:03 PM, Mike Frysinger <vapier@gentoo.org> wrote:
>>> On Monday, October 03, 2011 18:57:28 Michael LIAO wrote:
>>>
>>> please don't top post
>>>
>>
>> sorry, it's my first post on mailing.
>>
>>>> Most examples would be related to tools generating code.
>>>>
>>>> Suppose you have a software package with several hard-coded fully
>>>> optimized assembly file for different targets. Your build system need
>>>> to know the current target as well as target ABI to select the correct
>>>> assembly file to build it. It even desirable if it includes a simple
>>>> script to help generate assembly code (like the one in OpenSSL), you'd
>>>> better know the target ABI to prepare proper glue code without
>>>> breaking ABI.
>>>
>>> hjlu posted examples to the x32 site as to handle this.  the only difference
>>> between x86_64 and x32 is the size of the pointers.
>>>
>>
>> Besides the pointer size, there are other differences like indirect
>> branch which need different code sequence on x32 and x64. Indirect
>> branch would be used in assembly code (yeah, concrete example would
>> valuable here but indirect branch should be used potentially and
>> possibly in assembly code.) If the assembly code use indirect branch,
>> it needs to know the target ABI and generate/use difference code path.
>>
>
> In assembly codes, most, if not all, of x86-64 indirect branch work fine for x32
>

that may cause the target IP out of the first 4G range if assembly
code won't follow x32 abi, e.g. indirect target is stored in a memory
location and assembly direct use 64-bit near absolute indirect call
with m64 opernad since the branch target is 32 bits in memory but that
call will read 64-bit value and result in garbage on high 32 bits of
the final IP.

>
> --
> H.J.
>

Re: new triplet for x32 psABI?

[Mike Frysinger]

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On Monday, October 03, 2011 23:26:25 Michael LIAO wrote:
> On Mon, Oct 3, 2011 at 5:46 PM, Mike Frysinger wrote:
> > in terms of asm code, it's still possible to use ifdef's to handle cases
> > where you truly need different code paths.
> 
> Yeah, we could have '#ifdef X32ABI" in assembly file to select
> different path. But, how to generate that macro, says X32ABI, based on
> autoconf to detect/select target (not only target architecture but
> also target ABI.).

you don't need to do it yourself.  please look at the x32 website near the 
bottom.  it shows you how to use ifdef's that gcc itself provides.
-mike

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Re: new triplet for x32 psABI?

[H.J. Lu]

On Mon, Oct 3, 2011 at 8:44 PM, Michael LIAO <michael.hliao@gmail.com> wrote:
> On Mon, Oct 3, 2011 at 5:53 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Mon, Oct 3, 2011 at 4:47 PM, Michael LIAO <michael.hliao@gmail.com> wrote:
>>> On Mon, Oct 3, 2011 at 4:03 PM, Mike Frysinger <vapier@gentoo.org> wrote:
>>>> On Monday, October 03, 2011 18:57:28 Michael LIAO wrote:
>>>>
>>>> please don't top post
>>>>
>>>
>>> sorry, it's my first post on mailing.
>>>
>>>>> Most examples would be related to tools generating code.
>>>>>
>>>>> Suppose you have a software package with several hard-coded fully
>>>>> optimized assembly file for different targets. Your build system need
>>>>> to know the current target as well as target ABI to select the correct
>>>>> assembly file to build it. It even desirable if it includes a simple
>>>>> script to help generate assembly code (like the one in OpenSSL), you'd
>>>>> better know the target ABI to prepare proper glue code without
>>>>> breaking ABI.
>>>>
>>>> hjlu posted examples to the x32 site as to handle this.  the only difference
>>>> between x86_64 and x32 is the size of the pointers.
>>>>
>>>
>>> Besides the pointer size, there are other differences like indirect
>>> branch which need different code sequence on x32 and x64. Indirect
>>> branch would be used in assembly code (yeah, concrete example would
>>> valuable here but indirect branch should be used potentially and
>>> possibly in assembly code.) If the assembly code use indirect branch,
>>> it needs to know the target ABI and generate/use difference code path.
>>>
>>
>> In assembly codes, most, if not all, of x86-64 indirect branch work fine for x32
>>
>
> that may cause the target IP out of the first 4G range if assembly
> code won't follow x32 abi, e.g. indirect target is stored in a memory
> location and assembly direct use 64-bit near absolute indirect call
> with m64 opernad since the branch target is 32 bits in memory but that
> call will read 64-bit value and result in garbage on high 32 bits of
> the final IP.
>

X32 assembler/linker should handle it properly by zero-extending address
to 64bit.

-- 
H.J.

Re: new triplet for x32 psABI?

[Michael LIAO]

On Mon, Oct 3, 2011 at 3:34 PM, Mike Frysinger <vapier@gentoo.org> wrote:
> On Monday, October 03, 2011 18:25:46 Michael LIAO wrote:
>> As x32 psABI (https://sites.google.com/site/x32abi/) is invented, do
>> we need a new triplet for system relies on triplet to figure out it's
>> targeted on x32 environment. The new triplet would look like
>> 'x86_64-unknown-linux-gnux32' for x32 vs 'x86_64-unknown-linux-gnu'
>> for regular 64-bit. This's similar to EABI added to ARM or PowerPC,
>> where 'arm-unknown-linux-gnueabi' vs. 'arm-unknown-linux-gnu'.
>
> do you have examples of why you need this ?
>
>> The current scheme documented on website
>> (https://sites.google.com/site/x32abi/) uses the existing triplet but
>> specify x32 ABI through compiler/linker options. It works for most
>> compilers aware of that, but how other tools not handling
>> compiler/linker options knows the current build is targeted on a
>> different environment?
>
> the mips people have been using a single tuple for multiple abis (n32 and
> n64), and it doesn't appear to have been a blocker for them ...

That's not true, at least to build glibc, you can use
'mips64-linux-gnuabi64' to specify a n64 build and
''mips64-linux-gnuabin32' for a n32 build without specifying compiler
option explicitly. I just figured this out from mips ports of glibc
from http://repo.or.cz/w/glibc-ports.git/blob/HEAD:/sysdeps/mips/preconfigure,
where both compiler option and triplet are checked and triplet is
preferred if they are not match.


> -mike
>

Re: new triplet for x32 psABI?

[Mike Frysinger]

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On Tuesday 11 October 2011 22:55:35 Michael LIAO wrote:
> On Mon, Oct 3, 2011 at 3:34 PM, Mike Frysinger <vapier@gentoo.org> wrote:
> > On Monday, October 03, 2011 18:25:46 Michael LIAO wrote:
> >> The current scheme documented on website
> >> (https://sites.google.com/site/x32abi/) uses the existing triplet but
> >> specify x32 ABI through compiler/linker options. It works for most
> >> compilers aware of that, but how other tools not handling
> >> compiler/linker options knows the current build is targeted on a
> >> different environment?
> > 
> > the mips people have been using a single tuple for multiple abis (n32 and
> > n64), and it doesn't appear to have been a blocker for them ...
> 
> That's not true, at least to build glibc, you can use
> 'mips64-linux-gnuabi64' to specify a n64 build and
> ''mips64-linux-gnuabin32' for a n32 build without specifying compiler
> option explicitly. I just figured this out from mips ports of glibc
> from
> http://repo.or.cz/w/glibc-ports.git/blob/HEAD:/sysdeps/mips/preconfigure,
> where both compiler option and triplet are checked and triplet is
> preferred if they are not match.

while it is true glibc has this code, it doesn't make my statements incorrect: 
a single tuple works just fine with mips for multiple ABIs.  if you look at 
other projects like gcc, it doesn't check this field at all.  so you're still 
right where you started: you still haven't shown any cases which necessitate a 
dedicated tuple.
-mike

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Re: new triplet for x32 psABI?

[Michael LIAO]

On Tue, Oct 11, 2011 at 9:21 PM, Mike Frysinger <vapier@gentoo.org> wrote:
> On Tuesday 11 October 2011 22:55:35 Michael LIAO wrote:
>> On Mon, Oct 3, 2011 at 3:34 PM, Mike Frysinger <vapier@gentoo.org> wrote:
>> > On Monday, October 03, 2011 18:25:46 Michael LIAO wrote:
>> >> The current scheme documented on website
>> >> (https://sites.google.com/site/x32abi/) uses the existing triplet but
>> >> specify x32 ABI through compiler/linker options. It works for most
>> >> compilers aware of that, but how other tools not handling
>> >> compiler/linker options knows the current build is targeted on a
>> >> different environment?
>> >
>> > the mips people have been using a single tuple for multiple abis (n32 and
>> > n64), and it doesn't appear to have been a blocker for them ...
>>
>> That's not true, at least to build glibc, you can use
>> 'mips64-linux-gnuabi64' to specify a n64 build and
>> ''mips64-linux-gnuabin32' for a n32 build without specifying compiler
>> option explicitly. I just figured this out from mips ports of glibc
>> from
>> http://repo.or.cz/w/glibc-ports.git/blob/HEAD:/sysdeps/mips/preconfigure,
>> where both compiler option and triplet are checked and triplet is
>> preferred if they are not match.
>
> while it is true glibc has this code, it doesn't make my statements incorrect:
> a single tuple works just fine with mips for multiple ABIs.  if you look at
> other projects like gcc, it doesn't check this field at all.  so you're still
> right where you started: you still haven't shown any cases which necessitate a
> dedicated tuple.

That's why the proposed new triplet won't break existing packages as,
if they are compliant to autoconf, they should check that field with
'gnu*' or just ignore it instead of an exact matching.

I am not asking a dedicated triplet for x32 to be used exclusively for
x32 package build. I am asking additional triplet with enough details
of execution environment (ABI definitely a necessary detail.) for
package which relies on triplet to tell that. At least that triplet
could be canonical and widely accepted for package really caring about
that instead of forcing all package checking compiler options. If a
package needs to support similar thing to mutlilib just like glibc,
that new triplet will simiplifies their decision.

gcc definitely is not that kind of package as it could be built to
support generate x86-64, x32 and i386 code with the same package and
need a runtime option to tell that.

- michael

> -mike
>

Re: new triplet for x32 psABI?

[Mike Frysinger]

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On Wednesday 12 October 2011 01:03:19 Michael LIAO wrote:
> I am not asking a dedicated triplet for x32 to be used exclusively for
> x32 package build. I am asking additional triplet with enough details
> of execution environment (ABI definitely a necessary detail.) for
> package which relies on triplet to tell that. At least that triplet
> could be canonical and widely accepted for package really caring about
> that instead of forcing all package checking compiler options. If a
> package needs to support similar thing to mutlilib just like glibc,
> that new triplet will simiplifies their decision.

> gcc definitely is not that kind of package as it could be built to
> support generate x86-64, x32 and i386 code with the same package and
> need a runtime option to tell that.

except that if gcc doesn't change its default ABI output, it doesn't make it 
terribly useful.  you still need to specify the -mabi flag whenever you execute 
gcc, thus the tuple is just noise.
-mike

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Re: new triplet for x32 psABI?

[H.J. Lu]

On Tue, Oct 11, 2011 at 10:03 PM, Michael LIAO <michael.hliao@gmail.com> wrote:
> On Tue, Oct 11, 2011 at 9:21 PM, Mike Frysinger <vapier@gentoo.org> wrote:
>> On Tuesday 11 October 2011 22:55:35 Michael LIAO wrote:
>>> On Mon, Oct 3, 2011 at 3:34 PM, Mike Frysinger <vapier@gentoo.org> wrote:
>>> > On Monday, October 03, 2011 18:25:46 Michael LIAO wrote:
>>> >> The current scheme documented on website
>>> >> (https://sites.google.com/site/x32abi/) uses the existing triplet but
>>> >> specify x32 ABI through compiler/linker options. It works for most
>>> >> compilers aware of that, but how other tools not handling
>>> >> compiler/linker options knows the current build is targeted on a
>>> >> different environment?
>>> >
>>> > the mips people have been using a single tuple for multiple abis (n32 and
>>> > n64), and it doesn't appear to have been a blocker for them ...
>>>
>>> That's not true, at least to build glibc, you can use
>>> 'mips64-linux-gnuabi64' to specify a n64 build and
>>> ''mips64-linux-gnuabin32' for a n32 build without specifying compiler
>>> option explicitly. I just figured this out from mips ports of glibc
>>> from
>>> http://repo.or.cz/w/glibc-ports.git/blob/HEAD:/sysdeps/mips/preconfigure,
>>> where both compiler option and triplet are checked and triplet is
>>> preferred if they are not match.
>>
>> while it is true glibc has this code, it doesn't make my statements incorrect:
>> a single tuple works just fine with mips for multiple ABIs.  if you look at
>> other projects like gcc, it doesn't check this field at all.  so you're still
>> right where you started: you still haven't shown any cases which necessitate a
>> dedicated tuple.
>
> That's why the proposed new triplet won't break existing packages as,
> if they are compliant to autoconf, they should check that field with
> 'gnu*' or just ignore it instead of an exact matching.
>
> I am not asking a dedicated triplet for x32 to be used exclusively for
> x32 package build. I am asking additional triplet with enough details
> of execution environment (ABI definitely a necessary detail.) for
> package which relies on triplet to tell that. At least that triplet
> could be canonical and widely accepted for package really caring about
> that instead of forcing all package checking compiler options. If a
> package needs to support similar thing to mutlilib just like glibc,
> that new triplet will simiplifies their decision.
>
> gcc definitely is not that kind of package as it could be built to
> support generate x86-64, x32 and i386 code with the same package and
> need a runtime option to tell that.
>

I see 3 separate issues:

1. The file name of an x32 binary package needs to be marked as x32.
2. Compilers need a switch to generate x32 code.
3. We need to configure a software package for x32.

Which problem are you trying to resolve? Please explain yours
if it isn't covered above.

-- 
H.J.

Re: new triplet for x32 psABI?

[Mike Frysinger]

On Wed, Oct 12, 2011 at 12:28, H.J. Lu <hjl.tools@gmail.com> wrote:
> 1. The file name of an x32 binary package needs to be marked as x32.

i would think this would be completely a package manager issue and out
of scope for any ABI project such as x32
-mike