Re: [Xen-devel] Design doc of adding ACPI support for arm64 on Xen - version 3

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.08.15 at 10:21, <zhaoshenglong@xxxxxxxxxx> wrote:

> 
> On 2015/8/18 16:15, Jan Beulich wrote:
>>>>> On 18.08.15 at 09:35, <zhaoshenglong@xxxxxxxxxx> wrote:
>>> Hi Jan,
>>>
>>> On 2015/8/18 13:14, Jan Beulich wrote:
>>>>>>> Shannon Zhao <zhaoshenglong@xxxxxxxxxx> 08/18/15 5:46 AM >>>
>>>>> On 2015/8/17 23:33, Jan Beulich wrote:
>>>>>>>>> On 14.08.15 at 16:59, <shannon.zhao@xxxxxxxxxx> 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".

And this is a requirement for Linux? I.e. it can't do with just the
Configuration Table (which architecturally would be more clean imo)?

Jan


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