[PATCH v2 3/3] arm: Change setup_dtb_prop to create nodes by offset and node name

Nikolaus Schulz nikolaus.schulz at avionic-design.de
Fri Apr 29 07:22:23 PDT 2016

setup_dtb_prop looks like a generic function that can find and add any
nodes, which need not be top-level in the DT.  In practice though, the
function is only used for the top-level /chosen node, and it can't add
nodes for which the parent doesn't exist.

So far, so good - but for adding a new node to the DT, the parent offset
need be passed to fdt_add_subnode.  Currently in setup_dtb_prop the
parent offset is unknown, and instead a bogus error code is passed to

Fix that by adding the parent offset as an extra function argument to
setup_dtb_prop, and change the handling of the /chosen node to operate
on a relative path plus (zero) offset instead of an absolute path. This
aligns setup_dtb_prop to the libfdt API, where functions commonly
operate with a parent offset plus child node name.

Signed-off-by: Nikolaus Schulz <nikolaus.schulz at avionic-design.de>
 kexec/arch/arm/kexec-zImage-arm.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/kexec/arch/arm/kexec-zImage-arm.c b/kexec/arch/arm/kexec-zImage-arm.c
index 3222dd3..6b548c3 100644
--- a/kexec/arch/arm/kexec-zImage-arm.c
+++ b/kexec/arch/arm/kexec-zImage-arm.c
@@ -274,8 +274,9 @@ int atag_arm_load(struct kexec_info *info, unsigned long base,
 	return 0;
-static int setup_dtb_prop(char **bufp, off_t *sizep, const char *node_name,
-		const char *prop_name, const void *val, int len)
+static int setup_dtb_prop(char **bufp, off_t *sizep, int parentoffset,
+		const char *node_name, const char *prop_name,
+		const void *val, int len)
 	char *dtb_buf;
 	off_t dtb_size;
@@ -290,14 +291,14 @@ static int setup_dtb_prop(char **bufp, off_t *sizep, const char *node_name,
 	dtb_size = *sizep;
 	/* check if the subnode has already exist */
-	off = fdt_path_offset(dtb_buf, node_name);
+	off = fdt_subnode_offset(dtb_buf, parentoffset, node_name);
 	if (off == -FDT_ERR_NOTFOUND) {
 		dtb_size += fdt_node_len(node_name);
 		fdt_set_totalsize(dtb_buf, dtb_size);
 		dtb_buf = xrealloc(dtb_buf, dtb_size);
 		if (dtb_buf == NULL)
 			die("xrealloc failed\n");
-		off = fdt_add_subnode(dtb_buf, off, node_name);
+		off = fdt_add_subnode(dtb_buf, parentoffset, node_name);
 	if (off < 0) {
@@ -548,7 +549,7 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
 				 *  Error should have been reported so
 				 *  directly return -1
-				if (setup_dtb_prop(&dtb_buf, &dtb_length, "/chosen",
+				if (setup_dtb_prop(&dtb_buf, &dtb_length, 0, "chosen",
 						"bootargs", command_line,
 						strlen(command_line) + 1))
 					return -1;
@@ -594,11 +595,11 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
 			start = cpu_to_be32((unsigned long)(initrd_base));
 			end = cpu_to_be32((unsigned long)(initrd_base + initrd_size));
-			if (setup_dtb_prop(&dtb_buf, &dtb_length, "/chosen",
+			if (setup_dtb_prop(&dtb_buf, &dtb_length, 0, "chosen",
 					"linux,initrd-start", &start,
 				return -1;
-			if (setup_dtb_prop(&dtb_buf, &dtb_length, "/chosen",
+			if (setup_dtb_prop(&dtb_buf, &dtb_length, 0, "chosen",
 					"linux,initrd-end", &end,
 				return -1;

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