u-boot/doc/README.chromium

1 Running U-Boot from coreboot on Chromebooks
4 U-Boot can be used as a secondary boot loader in a few situations such as from
8 This document aims to provide a guide to booting U-Boot on a Chromebook. It
10 placing this information in the U-Boot tree should make it easier to find for
11 those who use U-Boot habitually.
13 Most of these platforms are supported by U-Boot natively, but it is risky to
17 For all of these the standard U-Boot build instructions apply. For example on
20    sudo apt install gcc-arm-linux-gnueabi
22    make O=b/nyan_big CROSS_COMPILE=arm-linux-gnueabi- nyan-big_defconfig all
26    https://drive.google.com/open?id=0B7WYZbZ9zd-3dHlVVXo4VXE2T0U
30 -----------------------------
34 https://www.chromium.org/chromium-os/firmware-porting-guide/using-nv-u-boot-on-the-samsung-arm-chro…
37 Nyan-big
38 --------
41 https://lists.denx.de/pipermail/u-boot/2015-March/209530.html
42 https://git.collabora.com/cgit/user/tomeu/u-boot.git/commit/?h=nyan-big
43 https://lists.denx.de/pipermail/u-boot/2017-May/289491.html
44 https://github.com/chromeos-nvidia-androidtv/gnu-linux-on-acer-chromebook-13#copy-data-to-the-sd-ca…
46 1. Build U-Boot
49    make -j8 O=b/nyan-big CROSS_COMPILE=arm-linux-gnueabi- nyan-big_defconfig all
58 used by U-Boot. This is because the Chromebook expects to pass it to the
64    ./b/nyan-big/tools/mkimage -f doc/chromium/nyan-big.its u-boot-chromium.fit
66    vbutil_kernel --arch arm --keyblock doc/chromium/devkeys/kernel.keyblock \
67 	--signprivate doc/chromium/devkeys/kernel_data_key.vbprivk \
68 	--version 1 --config dummy.txt --vmlinuz u-boot-chromium.fit \
69 	--bootloader dummy.txt --pack u-boot.kpart
76    sudo cgpt add -b 34 -s 32768 -P 1 -S 1 -t kernel $DISK
77    sudo cgpt add -b 32802 -s 2000000 -t rootfs $DISK
81 5. Write U-Boot to the SD card
83    sudo dd if=u-boot.kpart of=/dev/sdc1; sync
89 do this, login as root (via Ctrl-Alt-forward_arrow) and type
92 Reboot the device with the SD card inserted. Press Clrl-U at the developer
95    U-Boot 2017.07-00637-g242eb42-dirty (May 22 2017 - 06:14:21 -0600)
97    Model: Acer Chromebook 13 CB5-311
98    Board: Google/NVIDIA Nyan-big, ID: 1
102    Tegra124 (Nyan-big) #
111 This is likely due to some problem with change-over of the serial driver
117 To check that you copied the u-boot.its file correctly, use these commands.
118 You should see that the data at 0x100 in u-boot-chromium.fit is the first few
119 bytes of U-Boot:
121    hd u-boot-chromium.fit |head -20
125    hd b/nyan-big/u-boot.bin |head
131 from the load address. If this changes, you either need to modify U-Boot to be
136 ----------------
140 1. Patch U-Boot
154 2. Build U-Boot
157    make -j8 O=b/chromebook_jerry CROSS_COMPILE=arm-linux-gnueabi- \
165    ./b/chromebook_jerry/tools/mkimage -f doc/chromium/chromebook_jerry.its \
166 	u-boot-chromium.fit
168    vbutil_kernel --arch arm --keyblock doc/chromium/devkeys/kernel.keyblock \
169 	--signprivate doc/chromium/devkeys/kernel_data_key.vbprivk \
170 	--version 1 --config dummy.txt --vmlinuz u-boot-chromium.fit \
171 	--bootloader dummy.txt --pack u-boot.kpart
181 do this, login as root (via Ctrl-Alt-forward_arrow) and type
184 Reboot the device with the SD card inserted. Press Clrl-U at the developer
187    U-Boot 2017.05-00649-g72acdbf-dirty (May 29 2017 - 14:57:05 -0600)
209 --------
213    See: https://www.chromium.org/chromium-os/packages/cros-flashrom
217 --------
219 Coreboot itself is not designed to actually boot an OS. Instead, a program
220 called Depthcharge is used. This originally came out of U-Boot and was then
222 include a very small part of the U-Boot command-line interface but is not
223 usable as a general-purpose boot loader.
226 itself, but instead relies on coreboot. This is similar to (in U-Boot) having
229 what settings are actually used. When chain-loading into U-Boot we must be
230 careful to reinit anything that U-Boot expects. If not, some peripherals (or
234 Finally, it supports only a subset of the U-Boot's FIT format. In particular
236 addresses. This means that U-Boot must be able to boot from whatever
239 (see above) must start at the same address as U-Boot's CONFIG_SYS_TEXT_BASE.