Re: Design doc of adding ACPI support for arm64 on Xen - version 5

From: "Jan Beulich" <JBeulich@suse.com>
To: Shannon Zhao <zhaoshenglong@huawei.com>,
	Shannon Zhao <shannon.zhao@linaro.org>
Cc: Hangaohuai <hangaohuai@huawei.com>,
	Ian Campbell <ian.campbell@citrix.com>,
	Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
	andrew@fubar.geek.nz,
	"Huangpeng (Peter)" <peter.huangpeng@huawei.com>,
	Julien Grall <julien.grall@citrix.com>,
	Stefano Stabellini <stefano.stabellini@citrix.com>,
	David Vrabel <david.vrabel@citrix.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	xen-devel <xen-devel@lists.xen.org>,
	Parth Dixit <parth.dixit@linaro.org>,
	Christoffer Dall <christoffer.dall@linaro.org>,
	RogerPau Monne <roger.pau@citrix.com>
Subject: Re: Design doc of adding ACPI support for arm64 on Xen - version 5
Date: Mon, 31 Aug 2015 01:39:57 -0600	[thread overview]
Message-ID: <55E420ED020000780009E2D4@prv-mh.provo.novell.com> (raw)
In-Reply-To: <55E10AEF.6020806@linaro.org>

>>> On 29.08.15 at 03:29, <shannon.zhao@linaro.org> wrote:
> On 2015/8/28 23:06, Jan Beulich wrote:
>>>>> On 28.08.15 at 11:45, <zhaoshenglong@huawei.com> wrote:
>>> Create only one ConfigurationTable to store VendorGuid and VendorTable.
>> 
>> What do you mean with "Create only one ..." - there is only one.
>> DYM "Create one additional Configuration Table entry ...", implying
>> that the Configuration Table will need to by copied too?
> 
> Sorry for the misunderstanding. I mean that it doesn't copy the original
> one and just creates a new ConfigurationTable.

If you don't copy the original one, how does Dom0 learn of what is
in the original one (ACPI being just one such element)? Right now I
can't see why you wouldn't copy the entire table and simply append
the one extra entry.

>>> d) Copy MADT table
>>> It needs to change MADT table to restrict the number of vCPUs. We choose
>>> to copy the first dom0_max_vcpus GICC entries of MADT to new created
>>> MADT table when numa is not supported currently.
>> 
>> Copy means you imply to have an original?
> 
> So I'll change it to "create".
> 
>> What if dom0_max_vcpus
>> is larger than the physical CPU count?
> 
> I think it only needs to care the cpu_interface_number, uid and mpidr
> field of GICC entry and other fields could be same with the host GICC
> entry. It could get the mpidr from the vCPU index.

You again suggest to use data from host entries, i.e. you leave
incompletely addressed the original question: "What source of
information do you intend to use when the Dom0's vCPU count is
higher than the host's pCPU count?"

>>> g) Copy RSDP table
>>> Change the value of xsdt_physical_address in RSDP table. As we create a
>>> new XSDT table and the address of XSDT is changed, so it needs to update
>>> the value of "xsdt_physical_address" in RSDP. So Dom0 could get the
>>> right XSDT table rather than the old one. And it needs to update the
>>> value of VendorTable in EFI Configuration Table which is created in
>>> above step a).
>> 
>> How is this last sentence related to the handling of RSDP?
> 
> Because the ACPI root address(i.e. the address of RSDP table) is stored
> in EFI Configuration Table.

With this I can only see you to refer to everything _except_ the last
sentence. The last sentence talks about VendorTable, which I continue
to not see to have a relation to ACPI/RSDP.

Jan