Re: [PATCH] Hexagon: Swap SIGRGMAX-1 and SIGRTMIN+1

[Peter Maydell <peter.maydell@linaro.org>]

On Tue, 19 Nov 2019 at 19:07, Taylor Simpson <tsimpson@quicinc.com> wrote:
>
> Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
> ---
>  linux-user/signal.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/linux-user/signal.c b/linux-user/signal.c
> index 5ca6d62..ce3d27f 100644
> --- a/linux-user/signal.c
> +++ b/linux-user/signal.c
> @@ -72,6 +72,14 @@ static uint8_t host_to_target_signal_table[_NSIG] = {
>         over a single host signal.  */
>      [__SIGRTMIN] = __SIGRTMAX,
>      [__SIGRTMAX] = __SIGRTMIN,
> +#ifdef TARGET_HEXAGON
> +    /*
> +     * Hexagon uses the same signal for pthread cancel as the host pthreads,
> +     * so cannot be overridden.
> +     * Therefore, we map Hexagon signal to a different host signal.
> +     */
> +    [__SIGRTMAX - 1] = __SIGRTMIN + 1,
> +#endif
>  };

This breaks other stuff, unfortunately, like Go binaries.
(Also, you now have two host signals mapped to the same
target signal; notice that the existing RTMAX/RTMIN
is a swap of the two slots.)

We need a generic solution for this, Hexagon is not the
only one with the problem. There's a patchset on list
from ages back that had a suggested approach, but
it needed review and work.

thanks
-- PMM