From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailserv2.iuinc.com (IDENT:qmailr@mailserv2.iuinc.com [206.245.164.55]) by puffin.external.hp.com (8.9.3/8.9.3) with SMTP id DAA29740 for ; Fri, 10 Nov 2000 03:24:11 -0700 Received: from parcelfarce.linux.theplanet.co.uk (HELO www.linux.org.uk) (root@195.92.249.252) by mailserv2.iuinc.com with SMTP; 10 Nov 2000 10:26:07 -0000 Received: from willy by www.linux.org.uk with local (Exim 3.13 #1) id 13uBG4-0003NY-00; Fri, 10 Nov 2000 10:18:08 +0000 Date: Fri, 10 Nov 2000 10:18:08 +0000 From: Matthew Wilcox To: Grant Grundler Cc: parisc-linux@thepuffingroup.com, jgarzik@mandrakesoft.com, davem@redhat.com Subject: Re: [parisc-linux] tulip DMA mapping Message-ID: <20001110101808.B11268@parcelfarce.linux.theplanet.co.uk> References: <200011092012.MAA06943@milano.cup.hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <200011092012.MAA06943@milano.cup.hp.com>; from grundler@cup.hp.com on Thu, Nov 09, 2000 at 12:12:25PM -0800 Sender: List-ID: On Thu, Nov 09, 2000 at 12:12:25PM -0800, Grant Grundler wrote: > 0 is a valid pci_map_single() return value when the system has an IO MMU. Oh dear. You can bet tulip won't be the only driver which assumes it isn't a valid return value. Can't our IOMMU code be limited in such a way that 0 is not a valid return value? Say, constrain all allocated addresses to the top half of the device bus? (um, just check me on this, map_single returns a device bus address, not a processor bus address, right?) > The system will panic before pci_map_single() will fail. > The driver needs to remember some other way if a buffer was mapped or not. > Or the Documentation/DMA-mapping.txt should be changed - ie add this > to the interface definition and I can reserve the 1st mapping > entry so no-one uses it. we should probably have a BAD_DMA_ADDR define which that array should be initialised to. it's a little late in 2.4 to go through and audit all the drivers again. > Should I be mailing Jeff Garzik directly? > Or can someone who knows Jeff point this out to him? i've cc'd jeff & dave miller on this. -- Revolutions do not require corporate support.