RTS dependency on POSIX signals

[Jason Dagit]

On Wed, Jul 1, 2015 at 3:14 PM, Jakub Zalewski <jakzale at gmail.com> wrote:

> Dear all,
>
> I am working on porting GHC to [native client](
> https://developer.chrome.com/native-client) and I am currently trying to
> figure out how to port the RTS.
>
> On POSIX systems RTS seems to depend on two POSIX signals: timer signal
> and interrupt signal; while native client has very limited POSIX signal
> support --- for instance it does not define *siginfo_t* (which is
> referenced in the base package).
>
> So far, I know how to deal with the dependency on the timer signal, as
> while browsing the source code in rts/posix/Itimer.c, I noticed that on iOS
> the timer is not using POSIX signals to implement the timer signal.
>
> I wanted to ask if there are any other POSIX signal dependencies in the
> RTS, and would it safe to disable any signal handling in the RTS if I know
> that there will be no interrupt signals sent to the RTS?
>

I don't know the answer to your question, but for an additional data point
 you might look at the HalVM: https://github.com/galoisinc/halvm

For the specific case of timers it may not be helpful (for all I know it
uses some xen magic to get a timer interrupt), but it should be similar to
native-client support in that the HalVM provides the RTS with a stripped
down libc.

Jason
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