A kernel level message passing service

[David Addison]

The Quadrics interconnect implements a security model which allows user
proceeses to execute in a virtual environment and only allows processes from
the same application to comuunicate with each other.  This is akin to what
the MMU does for you on a single node, and in the same way it is the kernel
which creates the translations in the Quadrics MMU.

This model safely supports multiple users accessing the hardware without
resorting to per message system calls and kernel involvement. The kernel can
also make use of the interconnect, and services such as NFS and IP have been
already been implemented over the interconnect, without compromising OS
security.

> Actually, almost all of the driver for high performance interconnects
> provides OS-bypass functionnalities. It's true for Myrinet, 
> SCI, Quadrics,
> VIA is finally one more flavour.
> 
> But you are right : it's a tradeoff between security and performance.
> Usually the systeme calls overhead for security is very small and out
> of the critical path. The kernel is the only way to protect 
> against other
> users in a multi-users environnment.
>