Hello,

I'm working on porting QEMU to HelenOS. QEMU uses an event loop which polls
for fired events and calls corresponding callbacks if there are any. In
POSIX systems this is achieved using pipe and select functions, on Windows
CreateEvent and WaitForObject is used. Sadly, it seems that waiting for
events is mixed with waiting for actual files which works fine on both
platforms, but prevents designing a separate event mechanism for HelenOS
(it would mean creating and altering lot of code of QEMU). So I decided
that implementing pipe and select for HelenOS could be the solution.

Has there already been an attempt to implement these functions (or similar
ones) on HelenOS? If not, I was thinking that TMPFS could offer the right
functionality for the pipe function, but I would have to generate names for
the files created by the pipe and probably destroy them at some point.
Select could be more tricky. I will need a support from VFS (potentially
from used filesystem driver) to implement that. The only function I have
found doing some kind of waiting is fd_wait consequently
vfs_wait_handle_internal - could someone elaborate on what this
function does? I will gladly put it in the code as an API comment.

Thank you, with regards,

Jan Mares
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