MS_ASYNC with MS_INVALIDATE

[Mark Terribile]

Greetings,

A friend asked me to run some Linux source on FreeBSD.  It simulates a data
pool management system he is using, and it includes a call msync(2) with
both the MS_ASYNC and MS_INVALIDATE flags.  FreeBSD does not allow this.
(I tested it on my 4.8 system; I'll have access to a 5.1 system on Monday.)
I ran it without the MS_ASYNC, and got very different results from the ones
he reported on Linux.  I'd like to be able to explain what's happening.

Would someone please shed some light on why this combination of flags is
disallowed, and what the intended semantics are?  I suspect that either I
or he has a subtle misunderstanding here.

I'm not a regular reader of freebsd-hackers, so I would especially appreciate
a direct copy of any reply.

Thank you all for your time.

    Mark Terribile
    materribile at yahoo.com


__________________________________
Do you Yahoo!?
Yahoo! Finance Tax Center - File online. File on time.
http://taxes.yahoo.com/filing.html