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 - version 5 Date: Wed, 2 Sep 2015 17:25:48 +0800 Message-ID: <55E6C09C.9010301@huawei.com> References: <55E02DC5.4090202@huawei.com> <55E05A2F.1090305@citrix.com> <55E1042C.6000308@linaro.org> <55E43E36.90108@citrix.com> <55E4428C.7020308@huawei.com> <55E449DA.6080309@citrix.com> <55E525A8.3010302@huawei.com> <55E58BC7.7090403@citrix.com> <55E59B77.2090905@huawei.com> <55E5AADB.70503@citrix.com> <55E690DC.6000303@huawei.com> <55E6C45002000078000D7CCA@prv-mh.provo.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <55E6C45002000078000D7CCA@prv-mh.provo.novell.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: Jan Beulich Cc: hangaohuai@huawei.com, ian.campbell@citrix.com, stefano.stabellini@eu.citrix.com, shannon.zhao@linaro.org, andrew@fubar.geek.nz, peter.huangpeng@huawei.com, julien.grall@citrix.com, stefano.stabellini@citrix.com, david.vrabel@citrix.com, boris.ostrovsky@oracle.com, xen-devel@lists.xen.org, parth.dixit@linaro.org, christoffer.dall@linaro.org, roger.pau@citrix.com List-Id: xen-devel@lists.xenproject.org On 2015/9/2 16:41, Jan Beulich wrote: >>>> Shannon Zhao 09/02/15 8:03 AM >>> >> >There are some descriptions in Documentation/arm64/booting.txt of Linux: >> > >> >"The Image must be placed text_offset bytes from a 2MB aligned base >> >address near the start of usable system RAM and called there. Memory >> >below that base address is currently unusable by Linux, and therefore it >> >is strongly recommended that this location is the start of system RAM. >> >At least image_size bytes from the start of the image must be free for >> >use by the kernel." >> > >>>From this, it says "Memory below that base address is currently unusable >> >by Linux". So if we put these tables below Dom0 RAM address and even >> >describe these regions as RAM, the Linux could not use them. > May I remind you that a design should not take specific guest OS > implementation details (which even for that one OS may change over time) > as the basis for decisions? Yeah, but I think it needs to evaluate the design to check if it's feasible and make people believe this design could work by giving an example. Otherwise, if the design could not work well with some guest OSes or it needs to do a lot of changes, maybe we could choose another way to do it with no or less changes. -- Shannon