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Hi,

I'm trying to configure gcc to be able to cross-compile both 32 and 64 bit code. Currently I do thisThis works okay for both 32 and 64 bit building, except that it only installs a single 64 bit version of libgcc.a. I could build and install 2 versions of gcc but I feel sure it should be possible to build a toolchain that does both. I've tried various targets including x86_64-pc-linux and x86_64-pc-elf. And I've even tried to make my own target.

I've been trying the --enable-multilib option but I feel I still need to do something else.

Can anyone tell me how to get both the 32 bit and 64 bit versions of libgcc.a built and installed ? Perhaps someone with a 64bit Linux machine ?

Thanks in advance.

You'll only get a libgcc for the target you originally compile. x86_64's libgcc won't have any i[1-8]86 code, and to my knowledge it isn't possible to compile one libgcc for two targets. This is the main reason we use two cross-compilers to distinguish x86_64 and i686 - with the added bonus that our build system just has to inspect the name of the cross-compiler to determine which target to build for.

We can also add i686-specific stuff to the GCC's "specs" file such as library selection, crtbegin/crtend generation, and even "default" compile options such as "-fPIC". These differ quite a bit in our system at least and the easiest way to solve that is having two cross-compilers.

Thanks. Yep I may have to go that way. Although I noticed just now when I build an x86_64-pc-linux target it does create a directory under libgcc called 32 (or something). This seems to contain the libgcc 32bit routines. However it doesn't seem to install. I'll have a bit of a look.

Also I used to have a 64 bit ubuntu machine and it could build both 32 and 64 bit apps. Not sure how it did that tho.

BTW, pcmattman, do you have your own TARGET defined or do you use one of the default (like x86_64-pc-elf) ones ?

We can also add i686-specific stuff to the GCC's "specs" file

Where is the specs file ?

BTW, pcmattman, do you have your own TARGET defined or do you use one of the default (like x86_64-pc-elf) ones ?

We define an [arch]-pedigree target for x86_64 and i686 (effectively following the OS Specific Toolchain stuff). Other architectures don't yet have an OS-specific cross-compiler.

The specs are usually built into the compiler, and are created from the "gcc/config/myos.h" file you create in the OS Specific Toolchain tutorial. The tutorial shows a very basic file but if you look at Linux's example you can significantly tweak the compiler to your heart's content.

Although I noticed just now when I build an x86_64-pc-linux target it does create a directory under libgcc called 32 (or something).

A quick inspection of the "config.host" file in libgcc shows stuff such as this: EDIT: Removed the "rawr" above, that was a placeholder for an answer and I forgot it was there

You may be able to get something that works for both yet, with a combination of host-specific configuration and the --enable-multilib flag. When in doubt, it never hurts to look around the build system.