From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: [PATCH v1 2/2] dma-mapping-common: add DMA attribute - DMA_ATTR_IOMMU_BYPASS Date: Tue, 03 Nov 2015 10:08:13 +1100 Message-ID: <1446505693.17404.20.camel@kernel.crashing.org> References: <1446039110.3405.212.camel@infradead.org> <20151102120659.GC4642@shamir-ThinkPad-T430> <1446495208.17404.11.camel@kernel.crashing.org> <5270615.Sf6ng964Qt@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5270615.Sf6ng964Qt@wuerfel> Sender: kvm-owner@vger.kernel.org List-Archive: List-Post: To: Arnd Bergmann Cc: Shamir Rabinovitch , David Woodhouse , Andy Lutomirski , Christian Borntraeger , linux-arch , Paolo Bonzini , Martin Schwidefsky , "linux-doc@vger.kernel.org" , Sebastian Ott , linux-s390 , Cornelia Huck , Joerg Roedel , Jonathan Corbet , KVM , Christoph Hellwig List-ID: On Mon, 2015-11-02 at 22:45 +0100, Arnd Bergmann wrote: > > Then I would argue for naming this differently. Make it an optional > > hint "DMA_ATTR_HIGH_PERF" or something like that. Whether this is > > achieved via using a bypass or other means in the backend not the > > business of the driver. > > > > With a name like that, who wouldn't pass that flag? ;-) xHCI for example, vs. something like 10G ethernet... but yes I agree it sucks. I don't like that sort of policy anywhere in drivers. On the other hand the platform doesn't have much information to make that sort of decision either. Cheers, Ben.