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

[Alejandro Vallejo <agarciav@xxxxxxx>]

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?

Cheers,
Alejandro