Re: Different approach - harder to understand

[Stefan Skoglund <stetson@ebox.tninet.se>]

Matthias Pfisterer wrote:
> 
> It now comes to areas in which I am not firm. To my knowledge, the hurd
> servers make heavy use of RPCs. But I'm not sure if the port mechanism
> itself are RPCs or RPCs are implemented on top of them. I think, it's
> now time for you to do the same as I do from time to time: Read the Mach
> manuals, read the GNU Hurd manual, and look at the source code.

Mach ports can be used as a basis for more intelligent RPC like
Ada rendezvous or monitors and so on.

> 
> > > There is another notable thing with (Mach) ports: a single port is not
> > > globally available in the system. It is rather only known to the task
> > > (for now, think of a task being something simular to a process) which
> > > created it and to tasks the port was explicitely passed to by the owner.

Which is really necessary for the sake of security remember that the
memory
management parts is builts around mach IPC. You wouldn't like seeing
a nasty guy crashing your programs ehhhh...

> >  We could say that each port has something like a userid/groupid
> > associated just like files on Linux, rigth !?
> 
> There is no direct relation. It is simular to tasks vs. processes: ports
> rights (there are read and write ones) are a low-level concept, whereas
> userids are a high-level concept. Ports are primarily for communication,
> the usage to identify entities is rather a side-effect used by the auth
> server (which does the mapping between, uids and ports, if I understood
> the issue correctly). Here, too, I can't tell you more details, read the
> manuals yourself.
> 

User-mode device drivers uses a send-right when controlling its device.
Which should support a very nice X11 server for once. You write
most of the driver as a normal user program and small part which
is then dropped into the Mach kernel. Which should all support very nice
debugging of device drivers and what is more:
a close integration of application programs and devices.


supports user-loadable device drivers and it s