Re: Clang arm64 build is broken

[Andrey Konovalov]

On Mon, May 14, 2018 at 6:24 PM, Nick Desaulniers
<ndesaulniers@xxxxxxxxxx> wrote:
> On Fri, Apr 20, 2018 at 7:59 AM Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> wrote:
>> On Fri, Apr 20, 2018 at 10:13 AM, Marc Zyngier <marc.zyngier@xxxxxxx>
> wrote:
>> >> The issue is that
>> >> clang doesn't know about the "S" asm constraint. I reported this to
>> >> clang [2], and hopefully this will get fixed. In the meantime, would
>> >> it possible to work around using the "S" constraint in the kernel?
>> >
>> > I have no idea, I've never used clang to build the kernel. Clang isn't
>> > really supported to build the arm64 kernel anyway (as you mention
>> > below), and working around clang deficiencies would mean that we leave
>> > with the workaround forever. I'd rather enable clang once it is at
>> > feature parity with GCC.
>
>> The fact that there are some existing issues with building arm64
>> kernel with clang doesn't sound like a good justification for adding
>> new issues :)
>
>> However in this case I do believe that this is more of a bug in clang
>> that should be fixed.
>
> Just to follow up with this thread;
>
> Support for "S" constraints is being (re-)added to Clang in:
> https://reviews.llvm.org/D46745

Hi Nick!

I can confirm that the latest clang (which includes this patch) is
able to build the kernel with CONFIG_KVM enabled.

Thanks!