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Diffstat (limited to 'include/configs/rpi-common.h')
-rw-r--r--include/configs/rpi-common.h16
1 files changed, 11 insertions, 5 deletions
diff --git a/include/configs/rpi-common.h b/include/configs/rpi-common.h
index 927bae7..29510f5 100644
--- a/include/configs/rpi-common.h
+++ b/include/configs/rpi-common.h
@@ -144,8 +144,14 @@
/*
* Memory layout for where various images get loaded by boot scripts:
*
- * scriptaddr can be pretty much anywhere that doesn't conflict with something
- * else. Put it low in memory to avoid conflicts.
+ * I suspect address 0 is used as the SMP pen on the RPi2, so avoid this.
+ *
+ * fdt_addr_r simply shouldn't overlap anything else. However, the RPi's
+ * binary firmware loads a DT to address 0x100, so we choose this address to
+ * match it. This allows custom boot scripts to pass this DT on to Linux
+ * simply by not over-writing the data at this address. When using U-Boot,
+ * U-Boot (and scripts it executes) typicaly ignore the DT loaded by the FW
+ * and loads its own DT from disk (triggered by boot.scr or extlinux.conf).
*
* pxefile_addr_r can be pretty much anywhere that doesn't conflict with
* something else. Put it low in memory to avoid conflicts.
@@ -159,11 +165,11 @@
* this up to 16M allows for a sizable kernel to be decompressed below the
* compressed load address.
*
- * fdt_addr_r simply shouldn't overlap anything else. Choosing 32M allows for
- * the compressed kernel to be up to 16M too.
+ * scriptaddr can be pretty much anywhere that doesn't conflict with something
+ * else. Choosing 32M allows for the compressed kernel to be up to 16M.
*
* ramdisk_addr_r simply shouldn't overlap anything else. Choosing 33M allows
- * for the FDT/DTB to be up to 1M, which is hopefully plenty.
+ * for any boot script to be up to 1M, which is hopefully plenty.
*/
#define ENV_MEM_LAYOUT_SETTINGS \
"fdt_addr_r=0x00000100\0" \