From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Grundler Date: Thu, 15 May 2003 21:17:13 +0000 Subject: [Linux-ia64] Re: 64 Bits DMA Addresses for Alloc Consistent Interfaces. 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 On Thu, May 15, 2003 at 01:19:40PM -0700, David S. Miller wrote: > Do not mix "must" parameters such as read/write protections with > "it would be nice if" flag bits. R/W "hints" is not required for ia64/parisc IOMMUs. AFAIK, only swiotlb requires it and ZX1 IOMMU support has a one performance optimization which makes use of R/W hint. In short, "must" only applies to some subset of working platforms. But in general I agree, hints should be useful to most architectures. Having too many platform specific hints becomes hell for driver writers. grant