Difference between revisions of "Beagleboard:U-boot partitioning layout 2.0"

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m (just two lines for a simple uEnv.txt)
m (uEnv.txt Rootfs Partition /boot/uEnv.txt)
Line 31: Line 31:
 
Simple:
 
Simple:
 
  uname_r = $(uname -r)
 
  uname_r = $(uname -r)
cmdline = stuff passed to command line "quiet"
 
  
 
Optional:
 
Optional:
 +
cmdline = stuff passed to command line "quiet"
 
  mmcroot = default(/dev/mmcblk0p2 ro fixrtc)
 
  mmcroot = default(/dev/mmcblk0p2 ro fixrtc)
  mmcroot = uuid(mmcroot=UUID=(actuall uuid)) (needs initrd.gz in most cases)
+
  mmcroot = UUID=(actual uuid) (needs initrd.img-$(uname -r) in most cases)
  rootfstype = default (ext4)
+
  rootfstype = default(ext4)
  optargs = default (blank)
+
  optargs = default(blank)
  
 
= Example Image =
 
= Example Image =
 
  http://rcn-ee.net/deb/testing/2014-07-03/bone-debian-jessie-console-2014-07-03-4gb.img.xz
 
  http://rcn-ee.net/deb/testing/2014-07-03/bone-debian-jessie-console-2014-07-03-4gb.img.xz

Revision as of 16:32, 3 July 2014

Goal: to create a more distro friendly default bootloader installed on the BeagleBone Black eMMC.

Based on: https://wiki.linaro.org/Platform/DeviceTreeConsolidation

Starting with u-boot: v2014.07 this will be default: Patch: https://github.com/RobertCNelson/Bootloader-Builder/blob/master/patches/v2014.07-rc4/0001-am335x_evm-uEnv.txt-bootz-n-fixes.patch

Partition layout

Boot Partition

96Mb fat16 boot (unmounted usually shared as a usb gadget)
MLO/u-boot.img (MLO might be hidden and u-boot.img might be thrown into ext4)
uEnv.txt (priority 1) (Optional)

Rootfs Partition

(everything else) ext4 rootfs: /
/boot/uEnv.txt (priority 2)
/boot/dtbs/$(uname -r)/*.dtb
/boot/vmlinuz-$(uname -r)
/boot/initrd.img-$(uname -r) (optional)

u-boot dtb search order

(1) Mainline: /boot/dtbs/$(uname -r)/*.dtb
(2) Debian: /usr/lib/linux-image-$(uname -r)/*.dtb
(3) Ubuntu: /lib/firmware/$(uname -r)/device-tree

uEnv.txt Boot Partition /uEnv.txt

set "uenvcmd" and you have full control

uEnv.txt Rootfs Partition /boot/uEnv.txt

Simple:

uname_r = $(uname -r)

Optional:

cmdline = stuff passed to command line "quiet"
mmcroot = default(/dev/mmcblk0p2 ro fixrtc)
mmcroot = UUID=(actual uuid) (needs initrd.img-$(uname -r) in most cases)
rootfstype = default(ext4)
optargs = default(blank)

Example Image

http://rcn-ee.net/deb/testing/2014-07-03/bone-debian-jessie-console-2014-07-03-4gb.img.xz