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Re: [PATCH v3 2/4] docs, xen/arm: Introduce static heap memory





On 07/09/2022 13:41, Michal Orzel wrote:


On 07/09/2022 14:32, Julien Grall wrote:
[CAUTION: External Email]

On 07/09/2022 13:12, Michal Orzel wrote:
Hi Julien,

Hi Michal,

On 07/09/2022 13:36, Julien Grall wrote:

Hi Henry,

While reviewing the binding sent by Penny I noticed some inconsistency
with the one you introduced. See below.

On 07/09/2022 09:36, Henry Wang wrote:
+- xen,static-heap
+
+    Property under the top-level "chosen" node. It specifies the address
+    and size of Xen static heap memory. Note that at least a 64KB
+    alignment is required.
+
+- #xen,static-heap-address-cells and #xen,static-heap-size-cells
+
+    Specify the number of cells used for the address and size of the
+    "xen,static-heap" property under "chosen".
+
+Below is an example on how to specify the static heap in device tree:
+
+    / {
+        chosen {
+            #xen,static-heap-address-cells = <0x2>;
+            #xen,static-heap-size-cells = <0x2>;

Your binding, is introduce #xen,static-heap-{address, size}-cells
whereas Penny's one is using #{address, size}-cells even if the property
is not "reg".

I would like some consistency in the way we define bindings. Looking at
the tree, we already seem to have introduced
#xen-static-mem-address-cells. So maybe we should follow your approach?

That said, I am wondering whether we should just use one set of property
name.

I am open to suggestion here. My only request is we are consistent (i.e.
this doesn't depend on who wrote the bindings).

In my opinion we should follow the device tree specification which states
that the #address-cells and #size-cells correspond to the reg property.

Hmmm.... Looking at [1], the two properties are not exclusive to 'reg'
Furthermore, I am not aware of any restriction for us to re-use them. Do
you have a pointer?

As we are discussing re-usage of #address-cells and #size-cells for custom properties 
that are not "reg",
I took this info from the latest device tree specs found under 
https://www.devicetree.org/specifications/:
"The #address-cells property defines the number of <u32> cells used to encode the 
address field in a child node's reg property"
and
"The #size-cells property defines the number of <u32> cells used to encode the size field 
in a child node’s reg property"

Right. But there is nothing in the wording suggesting that #address-cells and #size-cells can't be re-used. From [1], it is clear that the meaning has changed.

So why can't we do the same?

Cheers,

--
Julien Grall



 


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