Messages in this thread | | | Date | Tue, 19 May 2020 19:47:36 -0700 | From | Nathan Chancellor <> | Subject | Re: [PATCH] READ_ONCE, WRITE_ONCE, kcsan: Perform checks in __*_ONCE variants |
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On Tue, May 19, 2020 at 10:28:41PM -0400, Qian Cai wrote: > > > > On May 19, 2020, at 6:05 PM, Thomas Gleixner <tglx@linutronix.de> wrote: > > > > Yes, it's unfortunate, but we have to stop making major concessions just > > because tools are not up to the task. > > > > We've done that way too much in the past and this particular problem > > clearly demonstrates that there are limits. > > > > Making brand new technology depend on sane tools is not asked too > > much. And yes, it's inconvenient, but all of us have to build tools > > every now and then to get our job done. It's not the end of the world. > > > > Building clang is trivial enough and pointing the make to the right > > compiler is not rocket science either. > > Yes, it all make sense from that angle. On the other hand, I want to be focus on kernel rather than compilers by using a stable and rocket-solid version. Not mentioned the time lost by compiling and properly manage my own toolchain in an automated environment, using such new version of compilers means that I have to inevitably deal with compiler bugs occasionally. Anyway, it is just some other more bugs I have to deal with, and I don’t have a better solution to offer right now.
Hi Qian,
Shameless plug but I have made a Python script to efficiently configure then build clang specifically for building the kernel (turn off a lot of different things that the kernel does not need).
https://github.com/ClangBuiltLinux/tc-build
I added an option '--use-good-revision', which uses an older master version (basically somewhere between clang-10 and current master) that has been qualified against the kernel. I currently update it every Linux release but I am probably going to start doing it every month as I have written a pretty decent framework to ensure that nothing is breaking on either the LLVM or kernel side.
$ ./build-llvm.py --use-good-revision
should be all you need to get off the ground and running if you wanted to give it a shot. The script is completely self contained by default so it won't mess with the rest of your system. Additionally, leaving off '--use-good-revision' will just use the master branch, which can definitely be broken but not as often as you would think (although I totally understand wanting to focus on kernel regressions only).
Cheers, Nathan
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