[Jikesrvm-core] Preempting IN_NATIVE threads using the timer

[Eliot M. <mo...@cs...>]

Dear Ian -- I wouldn't try the handle signals on the given thread's
stack. I'd use the alt stack mechanism and then manipulate the context and
the stack to make it appear that the thread called a routine we have set up
to do the processing, i.e., to come back into our scheduler and switch to
another thread. This gives better control, I think, and will leave less
stuff on the stack to confuse a stack walker. It was what I was trying to
suggest before. It is analogous to what we do in the case of a null pointer
deference: the signal handler forces a call to a routine whose only
function is to construct and then throw the suitable exception
object. Given that we made _that_ work, this strategy seems to me a better
idea than leaving signal handling stuff on a thread stack ....

Best wishes -- Eliot