On Thu, Sep 29, 2016 at 04:32:15PM -1000, Brent W. Baccala wrote: > 'netmsg' is progressing nicely. I'm developing a test suite for it, and > have encountered an oblique case that's causing me some grief. > > The problem is related to NO SENDERS notifications, which currently remain > attached to a port if its receive right is moved. This contrasts with the > behavior of DEAD NAME notifications, which seem not to remain attached to a > send right when it moves, and instead generate a PORT DELETED notification > if the process's last send right is moved (or destroyed). > > The Mach 3 kernel interfaces document, on page 60, includes the following > statement: > > (Note: Currently, moving a receive right does not affect any extant > no-senders notifications. It is currently planned to change this so that > no-senders notifications are canceled, with a send-once notification sent > to indicate the cancellation.) > > Well, this is exactly the situation that I'm wrestling with now. Tracking > NO SENDERS notifications across a network connection is a big headache. It > would be a lot easier if the behavior was changed as planned. > > I don't even have to change the kernel to implement that behavior in > 'netmsg'. I can trigger that cancellation message myself, by just > destroying the send-once right. > > Of course, then the behavior would differ depending on whether you moved a > receive right locally or remotely. Notifications would follow local moves, > but trigger cancellation on remote moves. Programs could not depend on > either behavior.
I don't believe the Hurd ever moves receive rights, and if it is, it's most certainly very limited and local. The design of the system simply doesn't need that feature. I completely understand the hassle you'd have to go through for this and I don't really see the benefit, so my opinion would be go ahead. -- Richard Braun
