From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH v3 2/2][BNX2]: Add iSCSI support to BNX2 devices. Date: Thu, 27 Sep 2007 04:22:15 -0400 Message-ID: <46FB6837.7040308@garzik.org> References: <20070908120036.GB8478@infradead.org> <20070909061551G.tomof@acm.org> <46F8C935.8050907@suse.de> <20070925133624H.tomof@acm.org> <46FB5C6B.3020506@garzik.org> <1190878682.30275.9.camel@pasglop> <46FB6087.10306@garzik.org> <1190880779.6158.0.camel@pasglop> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: FUJITA Tomonori , hare@suse.de, open-iscsi@googlegroups.com, hch@infradead.org, davem@davemloft.net, mchristi@redhat.com, netdev@vger.kernel.org, anilgv@broadcom.com, talm@broadcom.com, lusinsky@broadcom.com, uri@broadcom.com, fujita.tomonori@lab.ntt.co.jp To: benh@kernel.crashing.org Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:48354 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751365AbXI0IWX (ORCPT ); Thu, 27 Sep 2007 04:22:23 -0400 In-Reply-To: <1190880779.6158.0.camel@pasglop> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Benjamin Herrenschmidt wrote: > On Thu, 2007-09-27 at 03:49 -0400, Jeff Garzik wrote: >> Benjamin Herrenschmidt wrote: >>> On Thu, 2007-09-27 at 03:31 -0400, Jeff Garzik wrote: >>>> A key problem I was hoping would be solved with your work here was >>>> the >>>> elimination of that post dma_map_sg() split. >>>> >>>> If I understood James and Ben correctly, one of the key problems was >>>> always in communicating libata's segment boundary needs to the IOMMU >>>> layers? >>> Yup. If we can put some constraint in struct device that the dma mapping >>> code can then look at ... we also need to ensure that what's passed in >>> for DMA'ing already matches those constraints as well since no-iommu >>> platforms will basically just keep the dma table as-is. >> That's a good point... no-iommu platforms would need to be updated to >> do the split for me. I suppose we can steal that code from swiotlb or >> somewhere. > > Doing the split means being able to grow the sglist... which the dma_* > calls can't do at least not in their current form. IMO one straightforward approach is for the struct scatterlist owner to provide a table large enough to accomodate the possible splits (perhaps along with communicate that table's max size to the IOMMU/dma layers). Jeff