From mboxrd@z Thu Jan 1 00:00:00 1970 From: Catalin Marinas Subject: Re: [PATCH v5 11/13] xen: introduce xen_alloc/free_coherent_pages Date: Thu, 5 Sep 2013 17:09:05 +0100 Message-ID: <20130905160905.GI11887@arm.com> References: <1377801154-29215-11-git-send-email-stefano.stabellini@eu.citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1377801154-29215-11-git-send-email-stefano.stabellini@eu.citrix.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Stefano Stabellini Cc: "konrad.wilk@oracle.com" , "xen-devel@lists.xensource.com" , "Ian.Campbell@citrix.com" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" List-Id: xen-devel@lists.xenproject.org On Thu, Aug 29, 2013 at 07:32:32PM +0100, Stefano Stabellini wrote: > xen_swiotlb_alloc_coherent needs to allocate a coherent buffer for cpu > and devices. On native x86 and ARMv8 is sufficient to call > __get_free_pages in order to get a coherent buffer, while on ARM we need > to call arm_dma_ops.alloc. Don't bet on this for ARMv8. It's not mandated for the architecture, so at some point some SoC will require non-cacheable buffers for coherency. -- Catalin