}
```
+An exhaustive list of what `miri` does not support is not available, as this could be
+an unbounded set with FFI and more. However `miri` will explicitly tell you when it finds
+something unsupported with an error:
+
+```
+error: unsupported operation: can't call foreign function: mach_timebase_info
+ --> /home/r/.rustup/toolchains/miri/lib/rustlib/src/rust/src/libstd/sys/unix/time.rs:239:13
+ |
+239 | mach_timebase_info(&mut info);
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't call foreign function: mach_timebase_info
+ |
+ = help: this is likely not a bug in the program; it indicates that the program performed an operation that the interpreter does not support
+ = note: inside call to `std::sys::unix::time::inner::info` at /home/r/.rustup/toolchains/miri/lib/rustlib/src/rust/src/libstd/sys/unix/time.rs:156:24
+ = note: inside call to `std::sys::unix::time::inner::Instant::checked_sub_instant` at /home/r/.rustup/toolchains/miri/lib/rustlib/src/rust/src/libstd/time.rs:263:9
+note: inside call to `std::time::Instant::duration_since` at tests/run-pass/time.rs:25:20
+ --> tests/run-pass/time.rs:25:20
+ |
+25 | let diff = now2.duration_since(now1);
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^
+ = note: inside call to `main` at /home/r/.rustup/toolchains/miri/lib/rustlib/src/rust/src/libstd/rt.rs:67:34
+```
+
+If you do not see an error like this, you are able to keep using `miri`!
+
### Running Miri on CI
To run Miri on CI, make sure that you handle the case where the latest nightly