Prebuilt gcc 12.1.0 with Bitmanip

[vhdlnerd]

I've using the prebuilt gcc 12.1.0 (from here - rv64imc-3.0.0 w/multilib).
In my makefile, I have this (before including the common.mk file):

RISCV_PREFIX  = riscv64-unknown-elf-
MARCH        ?= rv32imc_zicsr
MABI         ?= ilp32

I have the neorv32 core built with the m and c options (and bitmanip). All my C code compiles/links fine -- no issues.

Now, I want to build with riscv bitmanip:

RISCV_PREFIX  = riscv64-unknown-elf-
MARCH        ?= rv32imc_zicsr_zbb_zba_zbc_zbs
MABI         ?= ilp32

The C compiler runs fine but I get an error during linking. Gcc is trying to link with the 64-bit version of libc.a instead of the 32-bit imc version.

I'm I missing something (a gcc switch or environment variable setting) or is the prebuilt gcc 12.1.0 toolchain not built to support this?

Note: I can do a workaround by copying the 32-bit imc versions of libc.a, libm.a and libgcc.a to my local lib directory and force gcc to link against them. (So, I know its possible to build with the bitmanip features enabled.) But, this "solution" is not ideal -- i.e., having toolchain libs in my local area.

Thanks,
Brian

[vhdlnerd]

I ended up building the GCC 13.x toolchain from source with just support for rv32imc_zicsr_zbb_zba_zbc_zbs and I'm using that now.

[stnolting]

Those multilib configuration are still exceeding my understanding of GCC's build system 😅

Just a note: you can also use the plain rv32i GCC toolchain and enable the different bit-manipulation extensions via the misa string. Thus, the compiler will compile your code emitting those additional instructions but the pre-compiled compiler libraries (let's say "math.h") were - well - precompiled using the rv32i only.

I ended up building the GCC 13.x toolchain from source with just support for rv32imc_zicsr_zbb_zba_zbc_zbs and I'm using that now.

👍

I think now that RISC-V GCC 13.1 is available I should update my prebuild toolchains...

[vhdlnerd]

You should wait a little on building RISC-V GCC 13.1, riscv-gnu-toolchain is not supporting 13.1, yet but they will soon. I did a "non-standard" 13.1 build because 12.2 had an issue build for rv32imc_zicsr_zbb_zba_zbc_zbs (see issue).

Those multilib configuration are still exceeding my understanding of GCC's build system

I don't know much about building toolchains, either. I just followed directions found here to make my 13.1 build.

[stnolting]

You should wait a little on building RISC-V GCC 13.1, riscv-gnu-toolchain is not supporting 13.1, yet but they will soon

Thanks for the hint!