Re: [PATCH] SN2 user-MMIO CPU migration

Grant Grundler
2006-01-24T07:04:21Z

On Tue, Jan 24, 2006 at 12:30:42AM -0600, Brent Casavant wrote:
> On Mon, 23 Jan 2006, Grant Grundler wrote:
> > Would an app first need to mmap an uncached address?
> > Or some other obvious "marker" that might warn the kernel?
>
> I'm not sure an uncached address would be appropriate, as I
> believe there are other non-IO uncached mappings which can
> be performed (whatever the fetchop stuff morphed into, for
> example -- I can't remember what its called now).

OK - just not many user space programs map uncache IO space.

> The only obvious marker I can thing of would be a flag in the
> mm struct set by a device driver when such a mapping occurs.

Device driver? Your original email only talks about user space:
http://marc.theaimsgroup.com/?l=linux-ia64&m\x113771591308925&w=2

Something that has to go through syscall/mmap and eventually
into IA64 specific code to setup a virtual address.
Or did I miss some later bit about a kernel driver?

> I can't think of any obviously correct state/flag to inspect,
> short of the other suggestion I made tonight.

ok. nevermind then...

grant