From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Grundler Date: Tue, 24 Jan 2006 07:04:21 +0000 Subject: Re: [PATCH] SN2 user-MMIO CPU migration Message-Id: <20060124070421.GA32132@esmail.cup.hp.com> List-Id: References: <20060118163305.Y42462@chenjesu.americas.sgi.com> In-Reply-To: <20060118163305.Y42462@chenjesu.americas.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org 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&m3771591308925&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