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

Alejandro Vallejo posted 12 patches 7 months, 3 weeks ago
There is a newer version of this series
[PATCH v4 11/12] xen/dt: ifdef out DEV_DT-related bits from device_tree.{c,h}
Posted by Alejandro Vallejo 7 months, 3 weeks ago 
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@amd.com>
---
 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 */
         }
     }
     if ( allnextpp )
diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
index b6d16756fc..ace7fc3274 100644
--- a/xen/include/xen/device_tree.h
+++ b/xen/include/xen/device_tree.h
@@ -108,9 +108,12 @@ struct dt_device_node {
      */
     struct list_head domain_list;
 
+#ifdef CONFIG_HAS_DEVICE_TREE_DISCOVERY
     struct device dev;
+#endif /* CONFIG_HAS_DEVICE_TREE_DISCOVERY */
 };
 
+#ifdef CONFIG_HAS_DEVICE_TREE_DISCOVERY
 #define dt_to_dev(dt_node)  (&(dt_node)->dev)
 
 static inline struct dt_device_node *dev_to_dt(struct device *dev)
@@ -119,6 +122,7 @@ static inline struct dt_device_node *dev_to_dt(struct device *dev)
 
     return container_of(dev, struct dt_device_node, dev);
 }
+#endif /* CONFIG_HAS_DEVICE_TREE_DISCOVERY */
 
 #define MAX_PHANDLE_ARGS 16
 struct dt_phandle_args {
-- 
2.43.0
Re: [PATCH v4 11/12] xen/dt: ifdef out DEV_DT-related bits from device_tree.{c,h}
Posted by Jan Beulich 7 months, 3 weeks ago 
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@amd.com>
> ---
>  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
Re: [PATCH v4 11/12] xen/dt: ifdef out DEV_DT-related bits from device_tree.{c,h}
Posted by Alejandro Vallejo 7 months, 3 weeks ago 
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@amd.com>
>> ---
>>  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
Re: [PATCH v4 11/12] xen/dt: ifdef out DEV_DT-related bits from device_tree.{c,h}
Posted by Jan Beulich 7 months, 3 weeks ago 
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@amd.com>
>>> ---
>>>  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
Re: [PATCH v4 11/12] xen/dt: ifdef out DEV_DT-related bits from device_tree.{c,h}
Posted by Stefano Stabellini 7 months, 3 weeks ago 
On Fri, 20 Jun 2025, 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@amd.com>

Same comment about renaming DOM0LESS_BOOT from this commit message if
there is a decision to rename that option. Other than that:

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

Patchew 2.1-devel-b67e4c2

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