Re: [PATCH] arm/docs: Clarify legacy DT bindings on UEFI

[Luca Fancellu <luca.fancellu@xxxxxxx>]

> On 13 Oct 2021, at 14:27, Julien Grall <julien@xxxxxxx> wrote:
> 
> Hi Luca,
> 
> On 13/10/2021 13:19, Luca Fancellu wrote:
>> Legacy compatible strings for dom0 modules are not
>> supported when booting using UEFI, the documentation
>> doesn't mention that.
> 
> Can you add a summary in the commit message why we consider the legacy 
> binding is not supported?

Yes what about:

Since the introduction of UEFI boot for Xen, the legacy
compatible strings were not supported and the stub code
was checking only the presence of “multiboot,module” to
require the Xen UEFI configuration file or not.
The documentation was not updated to specify that behavior.

Add a phrase to docs/misc/arm/device-tree/booting.txt
to clarify it.

> 
>> Add a phrase to docs/misc/arm/device-tree/booting.txt
>> to clarify it.
>> Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
>> ---
>>  docs/misc/arm/device-tree/booting.txt | 2 ++
>>  1 file changed, 2 insertions(+)
>> diff --git a/docs/misc/arm/device-tree/booting.txt 
>> b/docs/misc/arm/device-tree/booting.txt
>> index c6a775f4e8..017c0f13eb 100644
>> --- a/docs/misc/arm/device-tree/booting.txt
>> +++ b/docs/misc/arm/device-tree/booting.txt
>> @@ -51,6 +51,8 @@ Each node contains the following properties:
>>      Xen 4.4 supported a different set of legacy compatible strings
>>      which remain supported such that systems supporting both 4.4
>>      and later can use a single DTB.
>> +    However when booting Xen using UEFI and Device Tree, the legacy
> 
> NIT: I would drop "and Device Tree" because this feels a bit redundant as 
> this compatible can only be used in the Device-Tree.

I will drop it

> 
>> +    compatible strings are not supported.
>>      - "xen,multiboot-module" equivalent to "multiboot,module"
>>      - "xen,linux-zimage"     equivalent to "multiboot,kernel"
> 
> Cheers,
> 
> -- 
> Julien Grall