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Date:   Mon, 26 Aug 2019 08:38:00 -0700
From:   Nathan Chancellor <natechancellor@gmail.com>
To:     Jason Gunthorpe <jgg@ziepe.ca>
Cc:     Nick Desaulniers <ndesaulniers@google.com>,
        Bernard Metzler <BMT@zurich.ibm.com>,
        Doug Ledford <dledford@redhat.com>, linux-rdma@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>
Subject: Re: [PATCH] rdma/siw: Use proper enumerated type in map_cqe_status
Message-ID: <20190826153800.GA4752@archlinux-threadripper>
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Hi Jason,

On Fri, Aug 23, 2019 at 11:24:27AM -0300, Jason Gunthorpe wrote:
> On Thu, Jul 11, 2019 at 10:30:30AM -0700, Nathan Chancellor wrote:
> > On Thu, Jul 11, 2019 at 02:18:08PM -0300, Jason Gunthorpe wrote:
> > > On Thu, Jul 11, 2019 at 10:16:44AM -0700, Nick Desaulniers wrote:
> > > > On Thu, Jul 11, 2019 at 6:39 AM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> > > > >
> > > > > On Thu, Jul 11, 2019 at 01:14:34AM -0700, Nathan Chancellor wrote:
> > > > > > Maybe time to start plumbing Clang into your test flow until it can get
> > > > > > intergrated with more CI setups? :) It can catch some pretty dodgy
> > > > > > behavior that GCC doesn't:
> > > > >
> > > > > I keep asking how to use clang to build the kernel and last I was told
> > > > > it still wasn't ready..
> > > > >
> > > > > Is it ready now? Is there some flow that will compile with clang
> > > > > warning free, on any arch? (at least the portion of the kernel I check)
> > > > 
> > > > $ make CC=clang ...
> > > > 
> > > > Let us know if you find something we haven't already.
> > > > https://clangbuiltlinux.github.io/
> > > > https://github.com/ClangBuiltLinux/linux/issues
> > > 
> > > What clang version?
> > > 
> > > Jason
> > 
> > You'll need clang-9 for x86 because of the asm-goto requirement (or a
> > selective set of reverts for clang-8) but everything else should be
> > good with clang-8:
> 
> The latest clang-9 packages from apt.llvm.org do seem to build the
> kernel, I get one puzzling warning under RDMA:
> 
> drivers/infiniband/hw/hfi1/platform.o: warning: objtool: tune_serdes()+0x1f4: can't find jump dest instruction at .text+0x118a

Any particular config that I should use to easily reproduce this?

> And a BPF one:
> 
> kernel/bpf/core.o: warning: objtool: ___bpf_prog_run()+0xd: sibling call from callable instruction with modified stack frame

I think this might be related to this?

https://lore.kernel.org/lkml/cf0273fb-c272-72be-50f9-b25bb7c7f183@windriver.com/

Cheers,
Nathan