Re: [Qemu-devel] [PATCH 03/11] target/sh4: Handle user-space atomics

[Aurelien Jarno]

On 2017-07-05 14:23, Richard Henderson wrote:
> For uniprocessors, SH4 uses optimistic restartable atomic sequences.
> Upon an interrupt, a real kernel would simply notice magic values in
> the registers and reset the PC to the start of the sequence.
> 
> For QEMU, we cannot do this in quite the same way.  Instead, we notice
> the normal start of such a sequence (mov #-x,r15), and start a new TB
> that can be executed under cpu_exec_step_atomic.
> 
> Reported-by: Bruno Haible  <address@hidden>
> LP: https://bugs.launchpad.net/bugs/1701971
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  target/sh4/cpu.h       |  21 ++++++--
>  target/sh4/helper.h    |   1 +
>  target/sh4/op_helper.c |   6 +++
>  target/sh4/translate.c | 137 
> +++++++++++++++++++++++++++++++++++++++++++------
>  4 files changed, 147 insertions(+), 18 deletions(-)

I haven't reviewed this patch in details, but note that it breaks
booting a system under qemu-system.

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
address@hidden                 http://www.aurel32.net