Re: Research using L4Hurd

[Neal H. Walfield]

> Using a microkernel doesn't necessarily reduce the need for locking.
> For instance Hurd file servers are heavily threaded (one thread for
> each open file),

This is not typically true.  You might be confusing this with select.
In this case, select sends an io_select rpc to each file descriptor it
is interested in polling.

> It might be possible to write servers in a more select-loopish
> fashion, without multithreading, but that's not the recommended way to
> do it on the Hurd, and I'm afraid it will be even more unnatural when
> moving to L4 and its syncronous ipc.

I think you are confused about L4 ipc.  Although the ipc is
synchronous, rpc do not have to be.  Which is to say, when the client
sends an ipc to a server, it blocks until either the supplied timeout
is reach or the server does a receive.  The client, however, is not
obliged to do a receive from the same server.  In fact, the client is
not required to do a receive at all.