From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt_Domsch@Dell.com Date: Tue, 14 Nov 2000 04:39:16 +0000 Subject: RE: [Linux-ia64] Simple Question Simple Answer Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Allow me to pass on some words of wisdom I received from Alan Cox a while back. Particularly for IA-64, the comment to use the new PCI DMA architecture (linux/Documentatation/DMA-mapping.txt) has become especially important, as >4GB systems will be fairly common, and many drivers I've seen (as of September) were limiting system memory to 4GB because they hadn't migrated to this yet. Thanks, Matt Alan Cox porting notes 6/12/2000 The 2.2 to 2.4 porting should be easy. The big points are: Remember to use pci_enable_device dev->base_address[foo]. is now dev->resource[foo].start and does not need masking for the flag bits cli()/sti() type locking is now right out. In 2.2 its bad in 2.4 its very very bad 8) Use the new scsi error handling - it really is a big win handling degrading setups. The scsi proc has changed If its a PCI irq allocate using SA_SHIRQ but you must now pass something other than NULL for the dev_id If you want it to work on stuff like ia64 it needs to be both 64bit clean and touch mmio space only using readb/readw/readl etc not by direct pointer references. If you want it to work with >4Gb of RAM you really want to use the new pci_alloc_consistent API - but I would worry about that once it works not before. Alan