From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: Design doc of adding ACPI support for arm64 on Xen - version 2 Date: Wed, 2 Sep 2015 12:27:19 +0100 Message-ID: <1441193239.26292.141.camel@citrix.com> References: <55C413D5.7000709@huawei.com> <55CA2077.2000706@citrix.com> <55CAB7D3.5050504@huawei.com> <1439369520.9747.311.camel@citrix.com> <55CB1033.4040509@citrix.com> <20150812113655.274e4fa9@bender> <1439378619.8356.17.camel@citrix.com> <55CB37F5.7060008@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <55CB37F5.7060008@citrix.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: Julien Grall , Stefano Stabellini , Andrew Turner Cc: Hangaohuai , "Huangpeng (Peter)" , xen-devel , Stefano Stabellini , Shannon Zhao , Jan Beulich , Shannon Zhao , Parth Dixit , Christoffer Dall List-Id: xen-devel@lists.xenproject.org On Wed, 2015-08-12 at 13:11 +0100, Julien Grall wrote: > On 12/08/15 12:23, Ian Campbell wrote: > > Strictly it is considered a separate thing, much like loader.efi, despite > > where it lives e.g. it is self contained and not allowed to call into the > > kernel proper except via the formal interface provided for the hand-off. > > > > That might seem like semantic quibbling, but I just want to clarify that > > the Linux and BSD approaches here are basically the same. > > > > Given that these device tree bindings are really just Linux's equivalent of > > the "a format the kernel understands" which BSD uses as described above. I > > don't know what format BSD uses, Linux just happened to have a DTB library > > handy... > > IIRC, on FreeBSD, the loader and the kernel is talking through a custom > format called metadata. There is no modification of device tree by the > loader. Right, and as I say above Linux's equivalent of "a custom format called metadata" is to declare a device tree binding. > Although, I would prefer to see a common interface between Xen and DOM0 > rather than implementing a custom one for each OS we will support. Agreed. > I have to think how everything will work together. AFAIK, on x86, the > loader is loading Xen and the FreeBSD kernel in the memory. The metadata > necessary for the kernel is passed as a multiboot entry. > > I will speak with Royger to see what we can do here. > > In the meantime, I think we should drop "linux," when we standardize > them to show that they are generic and not linux specific. "we" here would be broader than just Xen of course. Ian.