From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shannon Zhao Subject: Re: Design doc of adding ACPI support for arm64 on Xen Date: Wed, 12 Aug 2015 11:10:32 +0800 Message-ID: <55CAB928.1090505@huawei.com> References: <55C0C17F.5040208@huawei.com> <55C1D783.3020908@huawei.com> <55C1F840.9060002@linaro.org> <55C20600.9070104@citrix.com> <55C2098A.6070300@linaro.org> <20150811204356.GG7765@l.oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150811204356.GG7765@l.oracle.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Konrad Rzeszutek Wilk , Shannon Zhao Cc: Hangaohuai , Ian Campbell , Stefano Stabellini , "Huangpeng (Peter)" , xen-devel , Julien Grall , Stefano Stabellini , Jan Beulich , parth.dixit@linaro.org, Christoffer Dall List-Id: xen-devel@lists.xenproject.org On 2015/8/12 4:43, Konrad Rzeszutek Wilk wrote: > On Wed, Aug 05, 2015 at 09:03:06PM +0800, Shannon Zhao wrote: >> >> >> On 2015/8/5 20:48, Julien Grall wrote: >>> On 05/08/15 12:49, Shannon Zhao wrote: >>>>>>> That's great! >>>>>>> Keep in mind that many ARM platforms have non-PCI busses, so I think >>>>>>> we'll need an amba and a platform bus_notifier too, in addition to the >>>>>>> existing pci bus notifier. >>>>>>> >>>>> >>>>> Thanks for your reminding. I thought about amba. Since ACPI of current >>>>> linux kernel doesn't support probe amba bus devices, so this >>>>> bus_notifier will not be used at the moment. But there are some voice >>>>> that we need to make ACPI support amba on the linux arm kernel mail >>>>> list. And to me it doesn't matter to add the amba bus_notifier. >>> This comment raised one question. What happen if the hardware has MMIO >>> region not described in the ACPI? >>> >> This sounds weird. If a device is described in ACPI table, it will not >> describe the MMIO region which the driver will use? Does this situation >> exist? >> >> If the hardware has mmio region not described in the ACPI, how does the >> driver know the region and use it? > > On the x86 world we would query the PCI configuration registers and read > the device BAR registers. Those would contain the MMIO regions the > device uses. > > But x86 is funny and you do say 'many .. ARM .. have non-PCI buses' - which > would imply you have not hit this yet. > > Are PCI devices interrogated differently on ARM? No configuration registers? >> For PCI devices, on ARM it will reuse the existing bus_notifier "xen_pci_notifier" to call hypercall to map mmio regions. And other operates are same with X86. Thanks, -- Shannon