gcc compiler option -m64

Roland Smith rsmith at xs4all.nl
Sun Aug 14 20:54:20 GMT 2005

On Sun, Aug 14, 2005 at 10:30:16PM +0200, O. Hartmann wrote:
> Hello.
> To make ist short: On my box (Athlon64 based machine) I run a FBSD 
> 6.0Beta2 with no 32Bit support and I hope (but do not exactly know) the 
> machine is 64Bit only that way without any 32Bit compatibilty.

I think the install CD doesn't come with 32bit stuff. If you want to be
absolutely sure, add NO_LIB32=true to /etc/make.conf and rebuild the

You can check the state of binaries with the file command:

$ file /bin/dd
/bin/dd: ELF 64-bit LSB executable, AMD x86-64, version 1 (FreeBSD), 
for FreeBSD 5.4-CURRENT (rev 2), dynamically linked (uses shared libs), 

To find all 32-bit binaries on your system:

find / -perm -100 -type f|xargs file|grep 32-bit|more

> I see in some compiler hints this undocumented '-m32' or '-m64' option 
> of  gcc(1) (undocumented that way as I can not find it in the man pages) 

It is documented in the gcc info files. The GNU people in general don't
like manpages.

> .  On SPARC64 systems, the system's default gcc compiler implies '-m64'. 
> Is this also true for AMD64 FreeBSD 6.X?


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