[Xen-devel] [PATCH 10/10] xen: strip /chosen/modules/module@<N>/* from dom0 device tree

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

These nodes are used by Xen to find the initial modules.

Only drop the "xen,multiboot-module" compatible nodes in case someone
else has a similar idea.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
v4 - /chosen/modules/modules@N not /chosen/module@N
v3 - use a helper to filter out DT elements which are not for dom0.
     Better than an ad-hoc break in the middle of a loop.
---
 xen/arch/arm/domain_build.c |   40 ++++++++++++++++++++++++++++++++++++++--
 1 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 6abbb03..512d78c 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -172,6 +172,40 @@ static int write_properties(struct domain *d, struct 
kernel_info *kinfo,
     return prop;
 }
 
+/* Returns the next node in fdt (starting from offset) which should be
+ * passed through to dom0.
+ */
+static int fdt_next_dom0_node(const void *fdt, int node,
+                              int *depth_out,
+                              int parents[DEVICE_TREE_MAX_DEPTH])
+{
+    int depth = *depth_out;
+
+    while ( (node = fdt_next_node(fdt, node, &depth)) &&
+            node >= 0 && depth >= 0 )
+    {
+        if ( depth >= DEVICE_TREE_MAX_DEPTH )
+            break;
+
+        parents[depth] = node;
+
+        /* Skip /chosen/modules/module@<N>/ and all subnodes */
+        if ( depth >= 3 &&
+             device_tree_node_matches(fdt, parents[1], "chosen") &&
+             device_tree_node_matches(fdt, parents[2], "modules") &&
+             device_tree_node_matches(fdt, parents[3], "module") &&
+             fdt_node_check_compatible(fdt, parents[3],
+                                       "xen,multiboot-module" ) == 0 )
+            continue;
+
+        /* We've arrived at a node which dom0 is interested in. */
+        break;
+    }
+
+    *depth_out = depth;
+    return node;
+}
+
 static int write_nodes(struct domain *d, struct kernel_info *kinfo,
                        const void *fdt)
 {
@@ -179,11 +213,12 @@ static int write_nodes(struct domain *d, struct 
kernel_info *kinfo,
     int depth = 0, last_depth = -1;
     u32 address_cells[DEVICE_TREE_MAX_DEPTH];
     u32 size_cells[DEVICE_TREE_MAX_DEPTH];
+    int parents[DEVICE_TREE_MAX_DEPTH];
     int ret;
 
     for ( node = 0, depth = 0;
           node >= 0 && depth >= 0;
-          node = fdt_next_node(fdt, node, &depth) )
+          node = fdt_next_dom0_node(fdt, node, &depth, parents) )
     {
         const char *name;
 
@@ -191,7 +226,8 @@ static int write_nodes(struct domain *d, struct kernel_info 
*kinfo,
 
         if ( depth >= DEVICE_TREE_MAX_DEPTH )
         {
-            printk("warning: node `%s' is nested too deep\n", name);
+            printk("warning: node `%s' is nested too deep (%d)\n",
+                   name, depth);
             continue;
         }
 
-- 
1.7.9.1


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