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From: Peter Maydell <peter.maydell@linaro.org>
Date: Sun, 20 Mar 2016 20:03:26 +0000
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Subject: Re: [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64
	targets
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To: Sean Bruno <sbruno@freebsd.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>, =?UTF-8?B?QWxleCBCZW5uw6ll?= <alex.bennee@linaro.org>, QEMU Developers <qemu-devel@nongnu.org>

On 20 March 2016 at 19:20, Sean Bruno <sbruno@freebsd.org> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA512
>
> aarch64 targets are now failing to build on i386 hosts due to missing
> __atomic_load_8() calls since this commit:
>
> https://github.com/qemu/qemu/commit/a0aa44b488b3601415d55041e4619aef5f3a4ba8#diff-c143d686899ae51d7b927d9c682e12fd
>
> I'm unsure if Linux is disabling aarch64 targets for i386 hosts or if
> this commit works "just fine" on Linux hosts right now, as it doesn't
> work with clang or gcc.

I think it just works on most Linux 32-bit architectures because
the compiler support can inline a suitable atomic op (there
is one case where it doesn't, which I think is PPC32).

In any case, we mustn't use atomics on types larger
than the host pointer type, because it's not portable enough.
Paolo or Alex, can you have a look at this?

thanks
-- PMM