Re: [OpenRISC] Removing architectures without upstream gcc support

[Philipp Wagner]

On 02/26/2018 09:00 AM, Arnd Bergmann wrote:
> On Sun, Feb 25, 2018 at 4:43 PM, Philipp Wagner
> <lists@xxxxxxxxxxxxxxxxxx> wrote:
> > Am 22.02.2018 um 16:45 schrieb Arnd Bergmann:
> > > While building the cross-toolchains, I noticed that overall, we can build almost
> > > all linux target architectures with upstream binutils and gcc these days,
> > > however there are still some exceptions, and I'd like to find out if anyone
> > > has objections to removing the ones that do not have upstream support.
> > > This are the four architectures I found:
> > > [...]
> > > * OpenRISC is a RISC architecture with a free license and an
> > >    active community. It seems to have lost a bit of steam after RISC-V
> > >    is rapidly taking over that niche, but there are chips out there and
> > >    the design isn't going away. Listing it here for completeness only
> > >    because there is no upstream gcc port yet, but this will hopefully
> > >    change in the future based on
> > >    https://lists.librecores.org/pipermail/openrisc/2018-January/000958.html
> > >    and I had no problems locating the gcc-7.x tree for building my
> > >    toolchains. The port is actively being maintained.
> >
> > It's mostly mentioned in the mailing list thread you linked to, but just
> > for completeness in this thread:
> >
> > The OpenRISC GCC port is maintained and regularly updated to newer GCC
> > versions. It is not, however, upstreamed to the FSF due to a single
> > missing FSF copyright assignment from a developer who has written large
> > parts of the initial port. All code which has copyright assignments in
> > place (binutils, GDB, etc.) has been upstreamed lately.
> >
> > For GCC, Stafford Horne is actively working on rewriting the parts which
> > we don't have the FSF copyright assignment for (and unless something
> > very surprising happens, won't get). [If anyone wants to help, there's
> > GSoC project for it as well:
> > https://fossi-foundation.org/gsoc18-ideas#openrisc-gcc-port]
> >
> > So I'd be very sad if the openrisc port gets dropped from Linux upstream.
>
> Yes, definitely. What I was really trying to say here is I consider openrisc
> an obvious exception to the 'no more ports without upstream gcc' rule
> because of the above.
>
> On a related note, has anyone successfully built an openrisc kernel with
> llvm/clang? As we discussed for arch/hexagon/, that architecture is unlikely
> to ever get an upstream gcc port, but like openrisc does have an upstream
> llvm port and they actually use that.

Actually the LLVM port of or1k isn't upstream either. CCing whitequark, 
who might know more about the (non-)plans of getting the backend 
upstream. I also don't know of anyone having tried to build the openrisc 
kernel with LLVM, would certainly be an interesting thing to try.

> I know that x86 and arm64 mostly work with llvm, arm32 works in some of
> the more common configurations at least (not big-endian or older CPUs
> though) and some others probably work as well. I have already build both
> gcc-5.5 and gcc-7.3 for openrisc and uploaded those to
> https://www.kernel.org/pub/tools/crosstool/files/bin/, but if llvm works as
> well, that could be one more reason to try to build a working set of
> clang based cross toolchains.

Philipp