README: document standard image variables
With these documented, we can start pushing towards standardizing their
use across boards.
Signed-off-by: Jason Hobbs <jason.hobbs@calxeda.com>
Cc: Mike Frysinger <vapier@gentoo.org>
diff --git a/README b/README
index 7e032a9..eb9ade9 100644
--- a/README
+++ b/README
@@ -3558,6 +3558,25 @@
Ethernet is encapsulated/received over 802.1q
VLAN tagged frames.
+The following image location variables contain the location of images
+used in booting. The "Image" column gives the role of the image and is
+not an environment variable name. The other columns are environment
+variable names. "File Name" gives the name of the file on a TFTP
+server, "RAM Address" gives the location in RAM the image will be
+loaded to, and "Flash Location" gives the image's address in NOR
+flash or offset in NAND flash.
+
+*Note* - these variables don't have to be defined for all boards, some
+boards currenlty use other variables for these purposes, and some
+boards use these variables for other purposes.
+
+Image File Name RAM Address Flash Location
+----- --------- ----------- --------------
+u-boot u-boot u-boot_addr_r u-boot_addr
+Linux kernel bootfile kernel_addr_r kernel_addr
+device tree blob fdtfile fdt_addr_r fdt_addr
+ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
+
The following environment variables may be used and automatically
updated by the network boot commands ("bootp" and "rarpboot"),
depending the information provided by your boot server: