mirror of
https://github.com/brain-hackers/u-boot-brain
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On all Pis so far, the VC FW provides a short stub to set up the ARM CPU
before entering the kernel (a/k/a U-Boot for us). This feature is not
currently supported by the VC FW when booting in 64-bit mode. However,
this feature will likely appear in the near future, and this U-Boot port
assumes that such a feature is in place. Without that feature, or a
temporary workaround described below, U-Boot will not boot.
Once the VC FW does provide the ARM stub, u-boot.bin built for rpi_3 can
be used drectly as kernel7.img, in the same way as any other RPi port. The
following config.txt is required:
# Fix mini UART input frequency, and setup/enable up the UART.
# Without this option, U-Boot will not boot, even if you don't care
# about the serial console. This option will always be required for
# all RPi3 use-cases, unless the PL011 UART is used, which is not
# yet supported by rpi_3* builds of U-Boot.
enable_uart=1
# Boot in AArch64 (64-bit) mode.
# It is possible that a future VC FW will remove the need for this
# option, instead auto-setting 32-/64-bit mode based on the "kernel"
# filename present on the SD card.
arm_control=0x200
Prior to the VC FW providing the ARM boot stub, you can use the following
steps to build an equivalent stub into the U-Boot binary:
git clone https://github.com/swarren/rpi-3-aarch64-demo.git \
../rpi-3-aarch64-demo
(cd ../rpi-3-aarch64-demo && ./build.sh)
Build U-Boot for rpi_3 in the usual way
cat ../rpi-3-aarch64-demo/armstub64.bin u-boot.bin > u-boot.bin.stubbed
Use u-boot.bin.stubbed as kernel7.img on the Pi SD card.
In this case, the following additional entries are required in config.txt:
# Tell the FW to load the kernel image at address 0, the reset vector.
kernel_old=1
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
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| .. | ||
| cpu | ||
| dts | ||
| imx-common | ||
| include | ||
| lib | ||
| mach-at91 | ||
| mach-bcm283x | ||
| mach-davinci | ||
| mach-exynos | ||
| mach-highbank | ||
| mach-integrator | ||
| mach-keystone | ||
| mach-kirkwood | ||
| mach-mvebu | ||
| mach-orion5x | ||
| mach-rockchip | ||
| mach-s5pc1xx | ||
| mach-snapdragon | ||
| mach-socfpga | ||
| mach-stm32 | ||
| mach-sunxi | ||
| mach-tegra | ||
| mach-uniphier | ||
| mach-versatile | ||
| mach-zynq | ||
| thumb1/include/asm/proc-armv | ||
| config.mk | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||