diff options
Diffstat (limited to 'rts/include')
| -rw-r--r-- | rts/include/rts/Config.h | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/rts/include/rts/Config.h b/rts/include/rts/Config.h index c5f34638e0..0f923205f5 100644 --- a/rts/include/rts/Config.h +++ b/rts/include/rts/Config.h @@ -44,7 +44,32 @@ Signals - supported on non-PAR versions of the runtime. See RtsSignals.h. -------------------------------------------------------------------------- */ +/* +Note [Lack of signals on wasm32-wasi] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +In the wasm32-wasi spec, there is no process/thread model, no +preemptive execution, and no posix-style asynchronous signals. See +WASI ticket #166 for upstream discussion about signal handling. + +In wasi-libc, signal.h includes an #error pragma in the default +setting that says: "wasm lacks signal support; to enable minimal +signal emulation, compile with -D_WASI_EMULATED_SIGNAL and link with +-lwasi-emulated-signal". It is possible to enable these flags when +configuring wasm32-wasi-ghc, but it still makes little sense, since +the emulation is really primitive and we might as well just stop +pretending signals exist at all. + +Therefore, in the entire GHC tree, whenever we define functionality +related to posix signals, we should add the CPP guards. When the +target lacks signals, we can't set signal handlers at all, and raising +a signal should degrade to exiting with the signal number as the exit +code. +*/ + +#if defined(HAVE_SIGNAL_H) #define RTS_USER_SIGNALS 1 +#endif /* Profile spin locks */ |