Re: Design doc of adding ACPI support for arm64 on Xen - version 2

[Shannon Zhao <zhaoshenglong@huawei.com>]

Hi Julien,

On 2015/8/12 0:19, Julien Grall wrote:
> Hi Shannon,
> 
> On 07/08/15 03:11, Shannon Zhao wrote:
>> 2. Create minimal DT to pass required information to Dom0
>> ----------------------------------------------------------
>> The minimal DT mainly passes Dom0 bootargs, address and size of initrd
>> (if available), address and size of uefi system table, address and size
>> of uefi memory table, uefi-mmap-desc-size and uefi-mmap-desc-ver.
>>
>> An example of the minimal DT:
>> / {
>>     #address-cells = <2>;
>>     #size-cells = <1>;
>>     chosen {
>>         bootargs = "kernel=Image console=hvc0 earlycon=pl011,0x1c090000
>> root=/dev/vda2 rw rootfstype=ext4 init=/bin/sh acpi=force";
>>         linux,initrd-start = <0xXXXXXXXX>;
>>         linux,initrd-end = <0xXXXXXXXX>;
>>         linux,uefi-system-table = <0xXXXXXXXX>;
>>         linux,uefi-mmap-start = <0xXXXXXXXX>;
>>         linux,uefi-mmap-size = <0xXXXXXXXX>;
>>         linux,uefi-mmap-desc-size = <0xXXXXXXXX>;
>>         linux,uefi-mmap-desc-ver = <0xXXXXXXXX>;
>>     };
>> };
>>
>> For details loook at
>> https://github.com/torvalds/linux/blob/master/Documentation/arm/uefi.txt
> 
> AFAICT, the device tree properties in this documentation are only used
> in order to communicate between the UEFI stub and Linux.
> 
> This means that those properties are not standardize and can change at
> any time by Linux folks. They don't even live in Documentation/devicetree/
> 
> I would also expect to see the same needs for FreeBSD running as DOM0
> with ACPI.
>
I'm not very clear about how FreeBSD communicates with UEFI. And when
booting with DT, how does FreeBSD communicate with UEFI? Not through
these properties?

> So it looks like to me that a generic name would be better for all those
> properties.
> 
If we change these name, it needs change some functions in Linux. Will
it impact the use of Linux with UEFI not on Xen?

Thanks,
-- 
Shannon