From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Grundler Date: Tue, 23 Apr 2002 21:11:37 +0000 Subject: Re: [Linux-ia64] Re: PCI DAC routines for SN 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 Jesse Barnes wrote: > He was the one that implemented it I thought. His assertion was that > since most chipsets don't handle 64 bit coherent allocations well, the > consistent interface should be forced to return a 32 bit address (is > that right Dave?). Right - HP recently changed ZX1 support based on the same assertion. And for the drivers I'm aware of (eg tg3, sym53c8xx), Dave is right. ... > otherwise I'd like to leave it up to the platform > (i.e. ia64/sn could return a 64 bit address and sparc64 could do 32). This is not feasible. The driver/device will use/support the same number of address bits regardless of architecture. If the architecture provides fewer bits than the driver/device supports, no problem obviously. I'm curious to see what happens with the pci_dac_alloc_consistent() idea. grant