From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: BUG: SCSI aic7xxx driver and AMD IOMMU Date: Thu, 26 Mar 2015 16:52:49 +0100 Message-ID: <20150326155248.GW4441@8bytes.org> References: <54E1FFFA.1060403@compro.net> <54F60D33.8090401@compro.net> <20150323150304.GQ4441@8bytes.org> <5511513D.6090106@compro.net> <20150325135937.GR4441@8bytes.org> <20150325151332.GT4441@8bytes.org> <5512E412.9040807@compro.net> <20150326124559.GV4441@8bytes.org> <55141E87.8040506@compro.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <55141E87.8040506@compro.net> Sender: linux-kernel-owner@vger.kernel.org To: Mark Hounschell Cc: iommu@lists.linux-foundation.org, Hannes Reinecke , "linux-scsi@vger.kernel.org >> SCSI development list" , linux-kernel@vger.kernel.org List-Id: linux-scsi@vger.kernel.org Hi Mark, On Thu, Mar 26, 2015 at 10:58:15AM -0400, Mark Hounschell wrote: > Sorry but CMA was still badly broken. I have a patch below that works. In which way is it broken? What happens when you try to allocate memory with dma_alloc_coherent? > I've tested it with small (no CMA) and large (with CMA) dma's using > dma_alloc_coherent. The patch below is just the "git diff" from your > cloned tree piped to a file then copied into this email. If you require > an official patch I can send one. Just let me know. The main differences I can spot are that you change the order (first CMA, then buddy) and you manually align the input size. I can see the reason for the later, but why does CMA need to be tried first? > Also, in my opinion, this CMA thing is clearly a BUG not a feature > request. The AMD iommu clearly breaks CMA. I feel what ever fix > you are happy with should be back ported to stable. It is not a BUG, the interface definition for dma_alloc_coherent does not specify that it can allocate infinite amounts of memory. So this patch does not qualify for stable. Joerg