Was unable to find riscv tool chain with "march=rv64imab" " mabi=lp64"

[kumarbrk9]

Hi,
I'm trying to explore on bitmanip instructions and require riscv tool chain with configurations "march=rv64imab" " mabi=lp64".

1. Can you please suggest where can I find latest version with mentioned configurations.
2. Else, will any of the following configurations work that I currently have?

• abi=lp64d -arch=rv64imafdc
• abi=lp64 arch=rv64i

3. Also can you help me in answering if I can untar and use it directly or any installation procedure need to be followed?

Thanks in advance.

Regards,
Kumar

[cmuellner]

There is no toolchain with -march=rv64imab as there is no single Bitmanip ISA extension.
You probably want the Zb* extensions (zba, zbb, zbc, zbs). Support for these extensions is upstream (and part of GCC 12.1).

[jim-wilson]

We don't have zb* support in riscv-gnu-toolchain as we haven't upgraded to gcc-12 yet. That release just happened a few days ago. We will probably wait a month or so for early bugs to be caught before we risk upgrading to a new version. You can try building riscv-gnu-toolchain using upstream gcc-12 sources. In theory that should work.

We only provide sources. There are some volunteers building packages. Recent enough Debian/Ubuntu has an embedded riscv cross compiler package you can install. Most Linux distros will have a linux riscv cross compiler package you can install, but it won't be multilib, so it will have only rv64gc/lp64d. There is a package for Windows called xPack GNU RISC-V Embedded GCC. But probably none of these use gcc-12 yet.

[kumarbrk9]

Hi cmuellner & wilson,
Thanks a lot for your kind responses.

As wilson mentioned "can try building riscv-gnu-toolchain using upstream gcc-12 sources.",
I've downloaded gcc 12.1 and is handy.
May I know what steps I need to follow next?

• where exactly can I find basic riscv tool chain
• how to install it and configure it with "march=rv64imab", " mabi=lp64"
• how can I link gcc 12.1?
  Sorry for asking very basic things. It would be great if anyone can post the steps to be followed.

Thanks in advance.

Regards,
Kumar

[cmuellner]

I propose that you use the build scripts of this repository and set the GCC sources to your local GCC 12 source directory (using the configure parameter --with-gcc-src=/path/to/gcc). E.g.:

./configure --prefix=/path/to/instdir --with-gcc-src=/path/to/gcc --with-arch=rv64gc --with-abi=lp64d
make -j$(nproc)

[kumarbrk9]

Hi cmuellner,
Thanks for all your time in giving a response with the clear picture. Will try it.

Regards,
Kumar

[kumarbrk9]

Hi cmuellner,

• we have to build gcc, mpc, gmp, mpfr, and binutils all separately for riscv? or above suggestion which you mentioned should work?
• If need to build separately, May I know the steps other than "configure" & "make" you mentioned above?

Thanks in advance.

Regards,
Kumar

[cmuellner]

This repository (riscv-gnu-toolchain) offers the possibility to override the location of the sources of the subprojects (GCC, Binutils, glibc, ...). This can be done by specifying the external sources at configure time (e.g. --with-gcc-src=/path/to/gcc or --with-binutis-src=/path/to/binutils). This is also documented in the README.md (at the end).

gmp and mpfr are dependencies and are expected to be installed on the host machine that builds the cross-toolchain. All dependencies are documented in the README.md (at the beginning).

So you can use this repository to build a toolchain with GCC 12.1 and Binutils 2.38 sources by downloading them separately and configuring where they can be found.

[kumarbrk9]

Hi cmuellner,

Tried the way you mentioned. But still I face multiple errors which start with
Assembler messages:
Error: cannot find default versions of the ISA extension `b'

I actually pointed to GCC 12.1.0. But still I face this error.
following was my command.
./configure --prefix=riscvtools_path --with-arch=rv64imab --with-abi=lp64 --with-gcc-src=path_to_gcc-12.1.0 --with-binutils-src=path_to_binutils-2.38

Can you please suggest any alternative approach if possible? that can help me install everything from scratch with configurations --with-arch=rv64imab --with-abi=lp64

[cmuellner]

As mentioned in my first response: rv64imab does not exist. There is no b extension, but there are zba, zbb, zbc, and zbs.

[kumarbrk9]

Hi cmuellner,

Have given a try with following command.
./configure --prefix=path_to_instdir --with-arch=rv64ima_zba_zbb_zbe_zbf_zbs_zicsr_zifencei --with-abi=lp64 --with-cmodel=medany --enable-multilib --with-gcc-src=path_to_gcc-12.1.0 --with-binutils-src=path_to_binutils-2.38

But facing following errors.
for i in argz/lib.a stdlib/lib.a ctype/lib.a search/lib.a stdio/lib.a string/lib.a signal/lib.a time/lib.a locale/lib.a reent/lib.a errno/lib.a misc/lib.a ssp/lib.a syscalls/lib.a machine/lib.a ; do
riscv64-unknown-elf-ar x ../$i;
done;
riscv64-unknown-elf-ar rc ../libc.a *.o
riscv64-unknown-elf-ar: ../argz/lib.a: No such file or directory
riscv64-unknown-elf-ar: ../stdlib/lib.a: No such file or directory
........
riscv64-unknown-elf-ar: ../syscalls/lib.a: No such file or directory
riscv64-unknown-elf-ar: ../machine/lib.a: No such file or directory
riscv64-unknown-elf-ar: *.o: No such file or directory
make[6]: *** [libc.a] Error 1

Can you please suggest what I'm missing out?

Thanks in advance

[kito-cheng]

zbe and zbf isn't supported on upstream binutils 2.38

[kumarbrk9]

Can you please suggest what version should I upgrade to, in order to get rid of errors?