Mixing 64 and 32-bit code (was: Linking amd64 binary with a
32-bit linux library)
cswiger at mac.com
Thu Aug 7 20:13:26 UTC 2008
On Aug 7, 2008, at 12:31 PM, Andrea Venturoli wrote:
>> You can't mix and match Linux and FreeBSD code in the same binary.
> Sorry for stepping in, but I have a similar question I asked in the
> past and didn't get any answer:
> is it possible to mix and match 32-bit and 64-bit FreeBSD code?
> I have a closed source 32-bit library which I'd like to link to on a
> 64-bit system...
The simplest answer is that it won't work-- the syscall interface and
function argument/return-value sizes are going to be different between
32-bit and 64-bit code.
If you have 32-bit code compiled with -fPIC which doesn't make any
system calls, and is using all C99 datatypes (rather than native
datatypes like "int" or "long" which are going to change in size under
an ILP64 environment), well, that might be linkable into a 64-bit
binary, but even so I wouldn't count on it to work without a
translation shim. 
: You can look up how thunking between Win16 and Win32 code worked
...but the same idea could be applied to generic 32-bit & 64-bit ELF
code. (It's really an evil thing to try to do, however.)
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