Re: [PATCH v4 11/12] xen/dt: ifdef out DEV_DT-related bits from device_tree.{c,h}

[Jan Beulich <jbeulich@xxxxxxxx>]

On 23.06.2025 15:18, Alejandro Vallejo wrote:
> On Mon Jun 23, 2025 at 9:44 AM CEST, Jan Beulich wrote:
>> On 20.06.2025 20:28, Alejandro Vallejo wrote:
>>> device-tree.c stops requiring CONFIG_HAS_DEVICE_TREE_DISCOVERY and may
>>> function with DOM0LESS_BOOT.
>>>
>>> Without this, there's a clash with x86's definition of device_t. Because
>>> x86 doesn't discover devices in the DT it can simply skip the code
>>> to do so during the unflattening phase.
>>>
>>> Not a functional change on architectures that currently use these files,
>>> as they already select CONFIG_HAS_DEVICE_TREE_DISCOVERY.
>>>
>>> Signed-off-by: Alejandro Vallejo <agarciav@xxxxxxx>
>>> ---
>>>  xen/common/device-tree/device-tree.c | 2 ++
>>>  xen/include/xen/device_tree.h        | 4 ++++
>>>  2 files changed, 6 insertions(+)
>>>
>>> diff --git a/xen/common/device-tree/device-tree.c 
>>> b/xen/common/device-tree/device-tree.c
>>> index 725ff71646..741e2ce585 100644
>>> --- a/xen/common/device-tree/device-tree.c
>>> +++ b/xen/common/device-tree/device-tree.c
>>> @@ -2029,9 +2029,11 @@ static unsigned long unflatten_dt_node(const void 
>>> *fdt,
>>>              ((char *)pp->value)[sz - 1] = 0;
>>>              dt_dprintk("fixed up name for %s -> %s\n", pathp,
>>>                         (char *)pp->value);
>>> +#ifdef CONFIG_HAS_DEVICE_TREE_DISCOVERY
>>>              /* Generic device initialization */
>>>              np->dev.type = DEV_DT;
>>>              np->dev.of_node = np;
>>> +#endif /* CONFIG_HAS_DEVICE_TREE_DISCOVERY */
>>>          }
>>>      }
>>
>> Without something said to that effect in the description, this contradicts
>>
>> obj-$(CONFIG_HAS_DEVICE_TREE_DISCOVERY) += device-tree/
>>
>> that the previous patch put in place, and that only the subsequent patch
>> will further change.
>>
>> Jan
> 
> Would replacing the last paragraph of the commit message with...
> 
>   Not a functional change because the whole file is gated by
>   CONFIG_HAS_DEVICE_TREE_DISCOVERY already. A later patch allows the file to 
> be
>   usable without it, for which this ifdefs are a prerequisite.
> 
> ... help?

Yes, afaic.

Jan