Re: [Qemu-devel] macOS 10.12 Sierra, Xcode 8 & clock_gettime()

[Peter Maydell]

On 25 October 2016 at 10:43, Liviu Ionescu <address@hidden> wrote:
> In Xcode 8 (more or less mandatory after upgrading to Sierra), Apple added 
> support for `clock_gettime(CLOCK_MONOTONIC, &ts)`, which is not bad in itself.
>
> Unfortunately, with this addition, a QEMU built on 10.12 runs **only** on 
> 10.12; on previous versions it fails with something like:
>
> ```
> $ ./qemu-system-gnuarmeclipse --version
> dyld: lazy symbol binding failed: Symbol not found: _clock_gettime
> Referenced from: /Applications/GNU ARM 
> Eclipse/QEMU/2.6.0-201610170917-dev/bin/./qemu-system-gnuarmeclipse (which 
> was built for Mac OS X 10.12)
> Expected in: /usr/lib/libSystem.B.dylib
> ```
>
> The explanation is simple, for previous versions `_clock_gettime` is not 
> available in the system library.
>
> Apple does some tricks with macros in `time.h` to specify that the 
> definitions were introduced in 10.12, but QEMU uses only `#ifdef 
> CLOCK_MONOTONIC` to select the use of `clock_gettime()`.
>
> Until a more elaborate solution will be considered, my workaround was to 
> replace `#ifdef CLOCK_MONOTONIC` with `#if defined(CLOCK_MONOTONIC) && 
> !defined(__APPLE__)` and so avoid references to `clock_gettime()`.

Does "build on 10.12, run on earlier versions" work apart from
that problem?

thanks
-- PMM