On 20.10.2015 09:36, David Holmes wrote:
On 20/10/2015 6:50 AM, Matthias Klose wrote:
I'm working around some build failures for zero targets, which fail to
build because the configury in openjdk tries to set -m32/-m64 on it's
own. I assume this behaviour was added for sun/oracle product builds to
build x86 and x86_64 targets on a x86_64 platform. The issue is that
the current configury checks if -m32/-m64 works with the current
compiler, and then enables it without losses. This breaks at least on
the x86_64-linux-gnux32 target. I assume it will break on other targets
as well, which don't recognize -m32/-m64, but usually use other options
like -mabi=<name>. Instead of hard-coding these flags for every
architecture, is there any chance for not passing these flags at all for
the default mode?
Part of the problem is that the default mode is not known ahead of time, your
gcc on your x64 system might be configured to build 32-bit by default.
is this really a common configuration? I don't know any Linux distribution
shipping such a compiler. The one possibility for a 32bit toolchain on a 64bit
host might be a x86 chroot created on a x86_64 host. But usually such build
environments are entered with a 32bit personality (see linux32(1)), hiding
anything build related from the host.
I would expect that the default mode is passed in some way as autoconf option,
or by setting CC="gcc -m64" (the latter unfortunately not working because CC is
expected to be a file name in some places).
If there is a better way to select this than -m32/-m64 then I'm happy to hear
it, but not sure if -march/-mabi gives us anything better on x86. What exactly
would you propose?
I'm not proposing to use -march/-mabi instead, but just avoiding -m32/-m64 at
all, unless you explicitly configure for it (e.g. --with-abi=<abi-option> ?).
Matthias
