Richard Henderson <r...@twiddle.net> writes:
> Allow qemu to build on 32-bit hosts without 64-bit atomic ops.
>
> Even if we only allow 32-bit hosts to multi-thread emulate 32-bit
> guests, we still need some way to handle the 32-bit guest using a
> 64-bit atomic operation. Do so by dropping back to single-step.
>
> Signed-off-by: Richard Henderson <r...@twiddle.net>
> ---
> configure | 33 +++++++++++++++++++++++++++++++++
> cputlb.c | 4 ++++
> tcg-runtime.c | 7 +++++++
> tcg/tcg-op.c | 22 ++++++++++++++++++----
> tcg/tcg-runtime.h | 46 ++++++++++++++++++++++++++++++++++++++++------
> tcg/tcg.h | 15 ++++++++++++---
> 6 files changed, 114 insertions(+), 13 deletions(-)
>
> diff --git a/configure b/configure
> index b4d3f90..1ab2e4a 100755
> --- a/configure
> +++ b/configure
> @@ -4479,6 +4479,35 @@ EOF
> fi
> fi
>
> +#########################################
> +# See if 64-bit atomic operations are supported.
> +# Note that without __atomic builtins, we can only
> +# assume atomic loads/stores max at pointer size.
> +
> +cat > $TMPC << EOF
> +#include <stdint.h>
> +int main(void)
> +{
> + uint64_t x = 0, y = 0;
> +#ifdef __ATOMIC_RELAXED
> + y = __atomic_load_8(&x, 0);
> + __atomic_store_8(&x, y, 0);
> + __atomic_compare_exchange_8(&x, &y, x, 0, 0, 0);
> + __atomic_exchange_8(&x, y, 0);
> + __atomic_fetch_add_8(&x, y, 0);
> +#else
> + char is_host64[sizeof(void *) >= sizeof(uint64_t) ? 1 : -1];
<snip>
This breaks with --enable-werror (and my Travis images):
config-temp/qemu-conf.c: In function ‘main’:
config-temp/qemu-conf.c:12:8: error: unused variable ‘is_host64’
[-Werror=unused-variable]
I'm not sure what the best fix is here? Pass -no-werror to the test compile?
--
Alex Bennée
