Commit dc0b7b0e authored by Jason Hobbs's avatar Jason Hobbs Committed by Wolfgang Denk
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README: document standard image variables

With these documented, we can start pushing towards standardizing their
use across boards.
Signed-off-by: default avatarJason Hobbs <>
Cc: Mike Frysinger <>
parent 4d91a6ec
......@@ -3558,6 +3558,25 @@ List of environment variables (most likely not complete):
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:
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