[U-Boot] [PATCH] fdt: Fix bug in size calculation in fdt_resize() with initrd use

[Stefan Roese <sr@denx.de>]

From: Feng Wang <fwang02@harris.com>

Original bug description from Feng (fdt_resize() bug caused "WARNING:
could not set linux, initrd-start FDT_ERR_NOSPACE."):

What I got is an error: "WARNING: could not set linux,initrd-start
FDT_ERR_NOSPACE." after loading Device Tree blob. This in turn caused
linux to miss init part.

After some digging, I found out the reason for this error, it is caused
by fdt_resize().

FDT blob got resized after filling in all board specific information of
PowerPC. (in boot_body_linux()). It reduced blob size with only extra
space for two fdt_reserve_entry, one for fdt itself, and one for initrd.
Then it's aligned to a 0x1000 page boundary. However, later in
fdt_initrd(), it could add two more properties, initrd-start AND
initrd-end, each one needs at least two fdt_reserve_entry sizes done by
_fdt_add_property() (name and value). Thus, the two fdt_reserve_entry
extra space is not sufficient.

So for some specific fdt size which is just under the page boundary
after resizing, this will cause an error of FDT_ERR_NOSPACE in
fdt_initrd() when setting those two properties, and failed to pass
initrd information to linux.

My fix is in fdt_resize(), leave at least 4 fdt_reserve_entry for
initrd. So instead of 2*sizeof(struct fdt_reserve_entry) for
actual_totalsize, use 5*sizeof(struc fdt_reserve_entry).

Stefan: I got this same error on katmai, when trying to boot with
initrd (run flash_self). This patch fixes this issue.

Signed-off-by: Feng Wang <fwang02@harris.com>
Tested-by: Stefan Roese <sr@denx.de>
Cc: Jerry Van Baren <gvb.uboot@gmail.com>
---
 common/fdt_support.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/common/fdt_support.c b/common/fdt_support.c
index 718b635..6f198de 100644
--- a/common/fdt_support.c
+++ b/common/fdt_support.c
@@ -498,11 +498,12 @@ int fdt_resize(void *blob)
 
 	/*
 	 * Calculate the actual size of the fdt
-	 * plus the size needed for two fdt_add_mem_rsv, one
-	 * for the fdt itself and one for a possible initrd
+	 * plus the size needed for 5 fdt_add_mem_rsv, one
+	 * for the fdt itself and 4 for a possible initrd
+	 * ((initrd-start + initrd-end) * 2 (name & value))
 	 */
 	actualsize = fdt_off_dt_strings(blob) +
-		fdt_size_dt_strings(blob) + 2*sizeof(struct fdt_reserve_entry);
+		fdt_size_dt_strings(blob) + 5 * sizeof(struct fdt_reserve_entry);
 
 	/* Make it so the fdt ends on a page boundary */
 	actualsize = ALIGN(actualsize + ((uint)blob & 0xfff), 0x1000);
-- 
1.7.2.1