Re: Configure Option to Disable libc

On Fri, 21 Nov 2025, 18:57 Shivam Patel via Gcc-help, <[email protected]>
wrote:

> Hi,
>
> For context, I'm working on a GCC backend for an extensible ISA.
> Here is a link to a previous thread I had made "Help Emitting Proper
> Immediates":
> https://gcc.gnu.org/pipermail/gcc-help/2025-November/144575.html.
> I've gotten further in the build process, but I am encountering the
> following error when running make all-target-libgcc:
>
> In file included from ../../../etca-gcc/libgcc/gthr.h:157,
>                  from ../../../etca-gcc/libgcc/unwind-dw2.c:37:
> ./gthr-default.h:35:10: fatal error: pthread.h: No such file or directory
>
>    35 | #include <pthread.h>
>       |          ^~~~~~~~~~~
> compilation terminated.
> make[1]: *** [unwind-dw2.o] Error 1
> make: *** [all-target-libgcc] Error 2
>
> I was wondering if there was a way to disable libc at configuration time as
> there isn't a libc for the target yet. Here is the exact configure line
> I've used:
>
> ../etca-gcc/configure \
> --target=etca-elf \
> --enable-languages=c \
> --without-headers \
> --prefix="$HOME/etca-compiler/out"
>
> I've tried a few fixes:
>
>
>   *
> Configuring with --disable-threads or --enable-threads=single
>

gthr-default.h will not try to include pthread.h if you use those options,
so my guess is that you didn't remove the whole build directory and start
again in a clean directory.


  *
> Adding tmakefile="${tmakefile} t-slibgcc-nolc-override" to config/gcc for
> the target
>   *
> Also tried configuring with --without-headers
>
> All of these have had no effect.


So I'm left with the following questions:
>
> 1. Is there a configure-time option (or some recommended approach) to
> prevent libgcc from requiring target libc headers
> like pthread.h when the target has no libc?
>
> 2. If not, what is the recommended minimal approach to build libgcc for a
> target
> without a libc? Should I be using --with-newlib
> or a different combination of options/overrides?
>


--without-headers --with-newlib should work


> Is there somewhere I can read documentation about the configure process,
> options, and/or makefile fragments that are available? I have not been able
> to find it but I am hopeful that it would answer other questions that may
> arise from my project.
>
> Thank you for any guidance!
>
> Best,
> Shivam
>