Re: [PATCH v3] tcg: Fix execution on Apple Silicon

[Roman Bolshakov]

On Fri, Jan 29, 2021 at 07:27:57PM -1000, Richard Henderson wrote:
> On 1/29/21 10:50 AM, Roman Bolshakov wrote:
> > 
> > I thought you already added MAP_JIT in 6f70ddee19e. It's getting enabled
> > on my M1 laptop. Was it intended or not?
> > 
> >     /* Applicable to both iOS and macOS (Apple Silicon). */
> >     if (!splitwx) {
> >         flags |= MAP_JIT;
> >     }
> > 
> > TCG from master branch of QEMU works fine on M1. I'm not sure why do we
> > need to duplicate it.
> 
> I thought there was something about abi/api build issues.  If there's nothing
> that needs doing, great!
> 

Hi Richard,

You're correct that older versions of OS X/macOS might not have MAP_JIT
definition, so a simple wrapping of the hunk with ifdef MAP_JIT might be
sufficient (or guard it for Big Sur and above):

  #if defined(MAC_OS_VERSION_11_0) && \
      MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_VERSION_11_0
      if (!splitwx && __builtin_available(macOS 11.0, *)) {
          flags |= MAP_JIT;
      }
  #endif

But I'm not sure if we want to support hosts older than 10.14.

Regards,
Roman