Re: [PATCH v2 0/9] iOS and Apple Silicon host support

[Thomas Huth]

On 19/10/2020 03.39, Joelle van Dyne wrote:
> These set of changes brings QEMU TCG to iOS devices and future Apple Silicon
> devices. They were originally developed last year and have been working in the
> UTM app. Recently, we ported the changes to master, re-wrote a lot of the 
> build
> script changes for meson, and broke up the patches into more distinct units.
> 
> A summary of the changes:
> 
> * `CONFIG_IOS` and `CONFIG_IOS_JIT` defined when building for iOS and
>   iOS specific changes (as well as unsupported code) are gated behind it.
> * A new dependency, libucontext is added since iOS does not have native 
> ucontext
>   and broken support for sigaltstack. libucontext is available as a new option
>   for coroutine backend.
> * On stock iOS devices, there is a workaround for running JIT code without
>   any special entitlement. It requires the JIT region to be mirror mapped with
>   one region RW and another one RX. To support this style of JIT, TCG is 
> changed
>   to support writing to a different code_ptr. These changes are gated by the
>   `CONFIG_IOS_JIT`.
> * For (recent) jailbroken iOS devices as well as upcoming Apple Silicon 
> devices,
>   there are new rules for applications supporting JIT (with the proper
>   entitlement). These rules are implemented as well.
> 
> Since v2:
> 
> * Changed getting mirror pointer from a macro to inline functions
> * Split constification of TCG code pointers to separate patch
> * Removed slirp updates (will send future patch once slirp changes are in)
> * Removed shared library patch (will send future patch)
> 
> -j
> 
> osy (9):
>   configure: option to disable host block devices
>   configure: cross-compiling without cross_prefix
>   qemu: add support for iOS host
>   coroutine: add libucontext as external library
>   tcg: add const hints for code pointers
>   tcg: implement mirror mapped JIT for iOS
>   tcg: mirror mapping RWX pages for iOS optional
>   tcg: support JIT on Apple Silicon
>   block: check availablity for preadv/pwritev on mac

Is there maybe also a way to compile-test this automatically in a macOS
container on Cirrus-CI or Travis, too? ... otherwise I'm a little bit afraid
that this support might bit-rot quite fast again, since most developers
don't have the corresponding setup...

 Thomas