Re: GNU Binutils 2.38 has been released

[Jim Wilson <jim.wilson.gcc@gmail.com>]

On Wed, Feb 23, 2022 at 9:31 AM Waldemar Brodkorb <wbx@openadk.org> wrote:

> Any other idea where to find this information. There is no
> mentioning of zicsr here:
>
> https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/config/riscv/t-linux-multilib;h=298547fee38b2b4062e7854c539aabd292927857;hb=39c0b8f1ac4be2fdaa309733bbae11fedc6b8b3d


Support for the CSR instructions were removed from the base architecture
over 3 years ago.  We didn't make the toolchain change at the time because
we recognized that it would be a mess.  We decided to fix the mess later.
However, over 3 years have gone by now, and no one volunteered to fix the
mess, so we unfortunately had to force the issue.  This was standing in the
way for the platform/profile changes which will be coming soon, and
required this change. This change was announced on the various toolchain
and linux mailing lists, including linux-kernel and linux-riscv, but
obviously there is no easy way to notify everyone.

You can find info about zicsr in the ISA manuals.
https://riscv.org/technical/specifications/
See chapter 9.

Here is a pointer to the announcement for the change.
http://lists.infradead.org/pipermail/linux-riscv/2022-January/011728.html

I don't follow the linux kernel mailing lists, but I believe patches to fix
this problem have already been posted.  Maybe they haven't been merged
yet.  They will need to be backported to older kernel versions if you want
to build them with newer toolchain versions.

Jim