> -----Original Message----- > From: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > Sent: Friday, April 23, 2021 4:40 PM > To: Brian Cain <bcain@xxxxxxxxxxxxxx> > Cc: Arnd Bergmann <arnd@xxxxxxxxxx>; open list:QUALCOMM HEXAGON... > <linux-hexagon@xxxxxxxxxxxxxxx>; clang-built-linux <clang-built- > linux@xxxxxxxxxxxxxxxx>; linux-arch <linux-arch@xxxxxxxxxxxxxxx>; Guenter > Roeck <linux@xxxxxxxxxxxx>; Randy Dunlap <rdunlap@xxxxxxxxxxxxx>; Miguel > Ojeda <miguel.ojeda.sandonis@xxxxxxxxx> > Subject: Re: ARCH=hexagon unsupported? > > On Fri, Apr 23, 2021 at 11:35 AM Brian Cain <bcain@xxxxxxxxxxxxxx> wrote: > > > > > -----Original Message----- > > > From: Arnd Bergmann <arnd@xxxxxxxxxx> > > > Sent: Friday, April 23, 2021 4:37 AM > > > To: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > > > Cc: open list:QUALCOMM HEXAGON... <linux-hexagon@xxxxxxxxxxxxxxx>; > > > clang-built-linux <clang-built-linux@xxxxxxxxxxxxxxxx>; Brian Cain > > > <bcain@xxxxxxxxxxxxxx>; linux-arch <linux-arch@xxxxxxxxxxxxxxx>; > > > Guenter Roeck <linux@xxxxxxxxxxxx> > > > Subject: Re: ARCH=hexagon unsupported? > > > > > > On Fri, Apr 23, 2021 at 12:12 AM 'Nick Desaulniers' via Clang Built > > > Linux <clang-built-linux@xxxxxxxxxxxxxxxx> wrote: > > > > > > > > Arnd, > > > > No one can build ARCH=hexagon and > > > > https://github.com/ClangBuiltLinux/linux/issues/759 has been open > > > > for > > > > 2 years. > > > > > > > > Trying to build > > > > $ ARCH=hexagon CROSS_COMPILE=hexagon-linux-gnu make LLVM=1 > > > LLVM_IAS=1 > > > > -j71 > > > > > > > > shows numerous issues, the latest of which commit 8320514c91bea > > > > ("hexagon: switch to ->regset_get()") has a very obvious typo > > > > which misspells the `struct` keyword and has been in the tree for > > > > almost 1 year. > > > > > > Thank you for looking into it. > > > > > > > Why is arch/hexagon/ in the tree if no one can build it? > > > > > > Removing it sounds reasonable to me, it's been broken for too long, > > > and we did the same thing for unicore32 that was in the same > > > situation where the gcc port was too old to build the kernel and the > > > clang port never quite work in mainline. > > > > > > Guenter also brought up the issue a year ago, and nothing happened. > > > I see Brian still occasionally sends an Ack to a patch that gets > > > merged through another tree, but he has not send any patches or pull > > > requests himself after taking over maintainership from Richard Kuo > > > in 2019, and the four hexagon pull requests after 2014 only > > > contained build fixes from developers that don't have access to the > > > hardware (Randy Dunlap, Viresh Kumar, Mike Frysinger and me). > > > > Nick, Arnd, > > > > I can appreciate your frustration, I can see that I have let the community > down here. I would like to keep hexagon in-tree and I am committed to > making the changes necessary to do so. > > I'm very happy to hear that. > > > I have a patch under internal review to address the cited build issues and > libgcc/compiler-rt content. > > We'd be first in line to help build test such a patch. Please consider cc'ing > myself and clang-built-linux@xxxxxxxxxxxxxxxx when such a patch is > available externally. Further, we have the CI ready and waiting to add new > architectures, even if it's just build testing. That would have caught > regressions like 8320514c91bea; we were down to 1 build failure with > https://github.com/ClangBuiltLinux/linux/issues/759 last I looked which was > preventing us from adding Hexagon to any CI, but we must now dig ourselves > out of a slightly deeper hole now. > > Is this patch something you suspect will take quite some time to work through > internal review? I don't think it should take long, no. I should have a better idea today of about how long it will take. We will share it ASAP. > > In addition, my team has been focusing on developing QEMU system mode > support that would mitigate some of the need for having hardware access. > We have landed support for userspace hexagon-linux in upstream QEMU. > > That's also great to hear. QEMU is a critical part of our CI for boot testing; if > there's more info on timelines or what's involved with booting a hexagon > kernel in QEMU, we'd be very happy to know how or when that's available. > > > My team and I want to make hexagon's open source footprint larger, not > smaller. I realize that not being a good steward of the hexagon kernel has not > helped, and we will do what we can to fix it. > > A worthwhile and appreciated sentiment. I believe you. > > Hexagon could be an interesting case for LLVM support in general for the > Linux kernel; a case where each target or driver need not necessarily have a > GCC backend to be acceptable. But barring anyone from being able to actually > build it (let alone run it), it's not that; it's less than that. It's dead code that bit > rots further and burdens maintainers who are maintaining something that's > already broken. I'm not sure who derives any benefit. > > I think it's in everyone's best interest to see Linux support more targets than > fewer, and 2020 has been a hard year, but I'm curious how long something > has to be broken before folks say "enough." Please let's support this properly > or recognize the situation for what it is. I don't think the special circumstances of 2020 are to blame, it's just my failure to give this work the priority it deserves. Agreed: we will support the target properly. -Brian
