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Re: [Xen-devel] [PATCH V1 08/29] xen/dts: Don't add a fake property "name" in the device tree



On 09/06/2013 05:28 PM, Ian Campbell wrote:
On Wed, 2013-08-28 at 15:47 +0100, Julien Grall wrote:
On new Flat Device Tree version, the property "name" may not exist.
The property is never used in Xen code except to set the field "name" of
dt_device_node.

For convenience, remove the fake property. It will save space during the
creation of the dom0 FDT.

Is it worth diverging from the Linux code this is based on over this
though?

If we don't diverge, I need to add some logic in device tree creation to know if the "name" property was generated by Xen.

The others solutions was:
   1) Add the logic during device tree creation
   2) Add a boolean to know if the property is a fake

Currently, the "name" property value is replicated in the name field of dt_device_node. Except staying close to Linux code, I don't see a good reason to create this fake property.


Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
---
  xen/common/device_tree.c |   21 +++++++++------------
  1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index be592d2..07a19ac 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -1543,6 +1543,7 @@ static unsigned long __init unflatten_dt_node(const void 
*fdt,
      if ( !has_name )
      {
          char *p1 = pathp, *ps = pathp, *pa = NULL;
+        char *tmp = NULL;
          int sz;

          while ( *p1 )
@@ -1556,25 +1557,21 @@ static unsigned long __init unflatten_dt_node(const 
void *fdt,
          if ( pa < ps )
              pa = p1;
          sz = (pa - ps) + 1;
-        pp = unflatten_dt_alloc(&mem, sizeof(struct dt_property) + sz,
-                                __alignof__(struct dt_property));
+
+        tmp = unflatten_dt_alloc(&mem, sz, 1);
          if ( allnextpp )
          {
-            pp->name = "name";
-            pp->length = sz;
-            pp->value = pp + 1;
-            *prev_pp = pp;
-            prev_pp = &pp->next;
-            memcpy(pp->value, ps, sz - 1);
-            ((char *)pp->value)[sz - 1] = 0;
-            dt_dprintk("fixed up name for %s -> %s\n", pathp,
-                       (char *)pp->value);
+            memcpy(tmp, ps, sz - 1);
+            np->name = tmp;
+            tmp[sz - 1] = 0;
+            dt_dprintk("fixed up name for %s -> %s\n", pathp, np->name);
          }
      }
+
      if ( allnextpp )
      {
          *prev_pp = NULL;
-        np->name = dt_get_property(np, "name", NULL);
+        np->name = (np->name) ? : dt_get_property(np, "name", NULL);
          np->type = dt_get_property(np, "device_type", NULL);

          if ( !np->name )




--
Julien Grall

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