Date: Thu, 31 Jul 2008 21:04:06 -0400 From: Chuck Robey <chuckr@telenix.org> To: Nate Eldredge <nge@cs.hmc.edu> Cc: freebsd-amd64@freebsd.org Subject: Re: app programming on freebsd amd64 Message-ID: <48926106.4010305@telenix.org> In-Reply-To: <Pine.LNX.4.64.0807311703260.1277@knuth.cs.hmc.edu> References: <4891F3F3.8090608@telenix.org> <20080731195527.GT1359@server.vk2pj.dyndns.org> <489243B0.80307@telenix.org> <20080731234107.GA99946@troutmask.apl.washington.edu> <Pine.LNX.4.64.0807311703260.1277@knuth.cs.hmc.edu>
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Nate Eldredge wrote:
> On Thu, 31 Jul 2008, Steve Kargl wrote:
>
>>> He's telling you that -m32 doesn't work because the necessary
>> run time support is missing.
>
> It's not really missing completely though. Just that gcc isn't set up
> to look for it in the right place.
>
OK, the flags you nicely gave me are enough to let me do my own experimentation,
so thanks. I'm quite used to things like -I, -L, -l, -g, like that, it's the
arch and machine options that I'm not as used to. Should see me on ARM options,
I am all over the road on that platform. Dangerous.
>>
>> troutmask:kargl[202] cat h.c
>> #include <stdio.h>
>> int main(void)
>> {
>> printf("Hello world!\n");
>> return 0;
>> }
>> troutmask:kargl[203] cc -o z h.c
>> troutmask:kargl[205] ldd z
>> z:
>> libc.so.7 => /lib/libc.so.7 (0x20063c000)
>> troutmask:kargl[206] file z
>> z: ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD), for FreeBSD
>> 8.0 (800040), dynamically linked (uses shared libs), FreeBSD-style,
>> not stripped
>> troutmask:kargl[207] cc -o z -m32 h.c
>> /usr/bin/ld: skipping incompatible /usr/lib/libgcc.a when searching
>> for -lgcc
>> /usr/bin/ld: skipping incompatible /usr/lib/libgcc.a when searching
>> for -lgcc
>> /usr/bin/ld: cannot find -lgcc
>
> nate@vulcan:/tmp$ gcc -c -m32 h.c
> nate@vulcan:/tmp$ gcc -v -o h -m32 h.o
> Using built-in specs.
> Target: amd64-undermydesk-freebsd
> Configured with: FreeBSD/amd64 system compiler
> Thread model: posix
> gcc version 4.2.1 20070719 [FreeBSD]
> /usr/bin/ld --eh-frame-hdr -m elf_i386_fbsd -V -dynamic-linker
> /libexec/ld-elf.so.1 -o h /usr/lib/crt1.o /usr/lib/crti.o
> /usr/lib/crtbegin.o -L/usr/local/lib -L/usr/local/lib -L/usr/lib
> -L/usr/lib h.o -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc
> --as-needed -lgcc_s --no-as-needed /usr/lib/crtend.o /usr/lib/crtn.o
> GNU ld version 2.15 [FreeBSD] 2004-05-23
> Supported emulations:
> elf_i386_fbsd
> elf_x86_64_fbsd
> /usr/bin/ld: skipping incompatible /usr/lib/libgcc.a when searching for
> -lgcc
> /usr/bin/ld: skipping incompatible /usr/lib/libgcc.a when searching for
> -lgcc
> /usr/bin/ld: cannot find -lgcc
>
> So it's still looking for things in /usr/lib when it should use
> /usr/lib32. We can call ld directly and give it the right things:
>
> nate@vulcan:/tmp$ /usr/bin/ld --eh-frame-hdr -m elf_i386_fbsd -V
> -dynamic-linker /libexec/ld-elf32.so.1 -o h /usr/lib32/crt1.o
> /usr/lib32/crti.o /usr/lib32/crtbegin.o -L/usr/lib32 h.o -lgcc
> --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s
> --no-as-needed /usr/lib32/crtend.o /usr/lib32/crtn.o
> GNU ld version 2.15 [FreeBSD] 2004-05-23
> Supported emulations:
> elf_i386_fbsd
> elf_x86_64_fbsd
> nate@vulcan:/tmp$ file ./h
> ./h: ELF 32-bit LSB executable, Intel 80386, version 1 (FreeBSD), for
> FreeBSD 7.0 (700055), dynamically linked (uses shared libs),
> FreeBSD-style, not stripped
> nate@vulcan:/tmp$ ./h
> Hello world!
>
> It might be that there is some set of options to gcc itself that would
> make the right thing happen here without calling ld directly. More
> likely someone would have to write a new specs file. But that's a
> relatively minor issue; the guts are there.
>
> Now it may be that the 32-bit runtime has bugs that would appear if we
> tried to do something more complicated. But it isn't totally absent.
>
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