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 3 Date: Tue, 18 Aug 2015 16:21:19 +0800 Message-ID: <55D2EAFF.20600@huawei.com> References: <55CE0247.4030805@linaro.org> <55D21AE2020000780009B6D4@prv-mh.provo.novell.com> <55D2A982.9000907@huawei.com> <55D2CD5A02000078000D6BD8@prv-mh.provo.novell.com> <55D2E03E.2060207@huawei.com> <55D305A9020000780009B942@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: <55D305A9020000780009B942@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 , shannon.zhao@linaro.org Cc: hangaohuai@huawei.com, ian.campbell@citrix.com, stefano.stabellini@eu.citrix.com, 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 List-Id: xen-devel@lists.xenproject.org On 2015/8/18 16:15, Jan Beulich wrote: >>>> On 18.08.15 at 09:35, wrote: >> Hi Jan, >> >> On 2015/8/18 13:14, Jan Beulich wrote: >>>>>> Shannon Zhao 08/18/15 5:46 AM >>> >>>> On 2015/8/17 23:33, Jan Beulich wrote: >>>>>>>> On 14.08.15 at 16:59, wrote: >>>>>> 1. Copy and change some EFI and ACPI tables >>>>>> ------------------------------------------- >>>>> >>>>> While some explanation on the reasons for this was given in the past >>>>> discussion, I'm still missing a word on the "why" for each of these here. >>>>> >>>>>> a) Copy EFI_SYSTEM_TABLE and change the value of FirmwareVendor, >>>>>> VendorGuid, VendorTable, ConfigurationTable. These changes are not very >>>>>> special and it just assign values to these members. >>>>> >>>>> I continue to question the need for fiddling with this table, not the >>>>> least because I don't see how you intend to hand it to the Dom0 >>>>> kernel: Are you expecting to call the kernel's ordinary EFI entry >>>>> point, despite it not itself running on EFI firmware? >>>>> >>>> Dom0 gets UEFI info from the minimal DT when booting with UEFI. >>>> And the main purpose to create a EFI_SYSTEM_TABLE is to provide the ACPI >>>> table root (RSDP) address to Dom0, so it could find the ACPI table. >>> >>> For that passing the configuration table would suffice. The more that Julien >>> in his reply said you're not even intending to use the kernel's EFI stub. >> I.e. >>> the question remains: How would you expect to hand the System Table >>> pointer to Dom0? >>> The System Table pointer will be passed to Dom0 through the minimal DT property "linux,uefi-system-table". >> >> Oh, I realize that there is some wrong expression about >> EFI_SYSTEM_TABLE. We don't copy all the EFI System Table, but only the >> EFI_SYSTEM_TABLE->Hdr. And assign the value of FirmwareVendor, set >> NumberOfTableEntries to 1. Create only one EFI Configuration Table to >> store Root table address. The other fields of EFI System Table stay >> zero. So Dom0 only gets the ACPI table through System Table, others will >> be invalid. > > While this makes it look even more hacky, it doesn't answer the > question. > > Jan > > > . > -- Shannon