From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Raymond Date: Tue, 22 Feb 2005 16:59:57 +0000 Subject: User Level I/O Message-Id: <20050222105957.B67472@goliath.americas.sgi.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Some embedded and I/O intensive applications prefer to do most of their I/O processing work in user space. They can do this through PIOs and mmap'ing their device registers. I'd like to present a feature that will allow them to handle interrupts in user space as well. SGI's User Level Interrupt (ULI) feature allows applications to safely do interrupt processing with user space handler functions. Applications get a high degree of control and a quick response (~3us) while ensuring that things like segfaults or infinite loops in the handler won't take down the OS. More information can be found at http://oss.sgi.com/projects/uli/. I have ULI patches for IA64 on 2.6.10 and 2.6.11-rc4. On the web page you can also find a support library, documentation, and very simple sample applications. The feature definitely isn't done yet but it's ready for people to start playing with. In particular, the code for handling infinite loops and supporting debugging is incomplete and the assembly needs to be cleaned up. Please take a look at this and let me know what you guys think. We'd like to get this integrated in 6.5.12 or soon after. Thanks, Michael -- Michael A. Raymond Office: (651) 683-3434 Core OS Group Real-Time System Software