Re: introduce --enable-mingw-full32 to default to --large-address-aware

[JonY <10walls@gmail.com>]

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On 11/07/2018 08:34 AM, Alexandre Oliva wrote:
> On Nov  1, 2018, JonY wrote:
> 
>> Looks like it causes an error on 64bit:
>> /usr/libexec/gcc/x86_64-w64-mingw32/ld: unrecognized option
>> '--large-address-aware'
> 
> What does?  The patch I suggested?  The current trunk?
> 
> What was the command in this case?  How was the toolchain configured?
> 
> 
> I've been looking into this, getting progressively puzzled, though I
> actually managed to duplicated the problem you mentioned, but only on
> x86_64-mingw32, NOT on x86_64-w64-mingw32.
> 
> 

No it's just a quick test to see how x86_64-w64-mingw32 reacts to
--large-address-aware, it doesn't play well.

> Here's what I found out in my investigation:
> 
> configured for i686-mingw32, GNU ld supports only the i386pe emulation,
> that supports the --large-address-aware flag.
> 
> Configured for x86_64-*-mingw32, it supports i386pe, but it defaults to
> i386pep, the 64-bit binary format, that does NOT support
> --large-address-aware.
> 
> x86_64-w64-mingw32 passes -mi386pe or -mi386pep to the linker, depending
> on -m32 or -m64, so the code to pass --large-address-aware to link -m32
> binaries in mingw-w64.h looks correct to me.  But x86_64-mingw32 does
> NOT use that: it uses the LINK_SPEC from mingw32.h, so it doesn't
> specify the emulation, ever.  That seems awfully broken to me.  If you
> ask for a 32-bit binary, using the default 64-bit linker format is
> unlikely to produce the desired results.
> 
> Is x86_64-mingw32 really supposed to be a usable target name?  It might
> even work as a 64-bit only target, but I don't see how its biarch
> support could possibly be functional.
> 
> If it is to be usable, is it really supposed to be different from
> x86_64-w64-mingw32?  Using mingw-w64.h besides mingw32.h would fix the
> biarch problems, but perhaps that's not desired for other reasons.
> 
> Fixing that is way beyond my knowledge or interest on Windows-based
> platforms, but given clarification as to whether x86_64-mingw32 is
> supposed to support biarch at all, I might be able to fix the
> implementation of --enable-large-address-aware there.
> 
> As for the problem you reported on x86_64-w64-mingw32, I'm afraid I'll
> need some more information to be able to duplicate that and try to fix
> it.
> 
> Thanks,
> 

x86_64-mingw32 is not used as far as I know, only with "w64" or "pc".

The "w64" carries a special meaning to gcc dating back to the early
64bit port. It basically tells gcc to use mingw-w64 specific features
that are not found on the regular mingw.org CRT at the time.

This might be affecting the "pc" vendor build, can you check
x86_64-pc-mingw32 just to see if it is affected?

Thanks.


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