low-priority xcall(9)s and preemption

[David Young <dyoung%pobox.com@localhost>]

The xcall(9) manual page says,

     xcall provides a mechanism for making ``low priority'' cross calls.  The
     function to be executed runs on the remote CPU within a thread context,
     and not from a software interrupt, so it can ensure that it is not inter-
     rupting other code running on the CPU, and so has exclusive access to the
     CPU.  Keep in mind that unless disabled, it may cause a kernel preemp-
     tion.

I take that last sentence to mean that a low-priority cross call *may*
preempt a thread on the remote CPU.  Is that correct?

In other words, can we rephrase that, "A low-priority cross call may
preempt a thread running on the remote CPU unless preemption is disabled
on that CPU."

Dave

-- 
David Young
dyoung%pobox.com@localhost    Urbana, IL    (217) 721-9981