U-Boot On RPi4
Building 64bit U-Boot (for RPi4)
wget https://snapshots.linaro.org/gnu-toolchain/12.0-2021.10-1/aarch64-linux-gnu/gcc-linaro-12.0.0-2021.10-x86_64_aarch64-linux-gnu.tar.xz
tar -xf gcc-linaro-12.0.0-2021.10-x86_64_aarch64-linux-gnu.tar.xz
export TOOLCHAIN=$(pwd)/gcc-linaro-12.0.0-2021.10-x86_64_aarch64-linux-gnu/bin
git clone [email protected]:u-boot/u-boot.git
cd u-boot/
git checkout v2021.10
ARCH=arm64 CROSS_COMPILE=$TOOLCHAIN/aarch64-linux-gnu- make rpi_4_defconfig
# Optionally modify config with menuconfig at this point
# ARCH=arm64 CROSS_COMPILE=$TOOLCHAIN/aarch64-linux-gnu- make menuconfig
ARCH=arm64 CROSS_COMPILE=$TOOLCHAIN/aarch64-linux-gnu- make -j8
The successful result is a u-boot.bin in the top-level folder of the u-boot source tree.
Using U-Boot
Listing files
Synopsis:
ls <interface> [<dev[:part]>] [directory]
List /boot files:
ls mmc 0:1
List / (rootfs) files:
ls mmc 0:2
Output:
<DIR> 4096 .
<DIR> 4096 ..
<DIR> 16384 lost+found
<DIR> 4096 boot
<DIR> 4096 bin
<DIR> 4096 dev
<DIR> 4096 etc
<DIR> 4096 home
<DIR> 4096 lib
<DIR> 4096 media
<DIR> 4096 mnt
<DIR> 4096 opt
<DIR> 4096 proc
<DIR> 4096 root
<DIR> 4096 run
<DIR> 4096 sbin
<DIR> 4096 srv
<DIR> 4096 sys
<DIR> 4096 tmp
<DIR> 4096 usr
<DIR> 4096 var
<DIR> 4096 boot.bak
Physical Memory
Synopsis:
md [.b, .w, .l, .q] address [# of objects]
Show first 0x80 bytes at address 0x0:
md.b 0x0 0x80
Output:
00000000: 40 05 00 58 1f 00 00 b9 01 00 b0 52 01 08 00 b9 @..X.......R....
00000010: 40 b0 39 d5 41 04 80 d2 00 00 01 aa 40 b0 19 d5 @.9.A.......@...
00000020: 80 04 00 58 00 e0 1b d5 7f e0 1c d5 e0 7f 86 d2 ...X............
00000030: 40 11 1e d5 20 b6 80 d2 00 11 1e d5 60 0e 80 d2 @... .......`...
00000040: 20 10 1e d5 00 08 80 d2 20 f2 19 d5 2d 00 00 94 ....... ...-...
00000050: 40 03 00 58 00 10 1c d5 20 79 80 d2 00 40 1e d5 @..X.... y...@..
00000060: 60 00 00 10 20 40 1e d5 e0 03 9f d6 a6 00 38 d5 `... @........8.
00000070: c6 04 40 92 e6 00 00 b4 05 03 00 10 5f 20 03 d5 ..@........._ ..
Booting The Kernel
# Set the kernel command line
setenv bootargs "8250.nr_uarts=1 console=ttyS0,115200 console=tty1 root=PARTUUID=42842715-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait maxcpus=4"
# Verify the kernel command line
env print bootargs
# View the /boot file listing
ls mmc 0:1
# Load the device tree blob
load mmc 0:1 $fdt_addr_r bcm2711-rpi-4-b.dtb
# Load the kernel (compressed) image
load mmc 0:1 $kernel_addr_r ORIGINALkernel8.img
# We have to setup scratch space for kernel decompression (if compressed)
# Note: We've chosen the high 0xb400000 bytes of DRAM
setenv kernel_comp_addr_r 0x30000000
setenv kernel_comp_size 0x0b400000
# Boot the kernel (The `-` denotes no initrd.)
booti $kernel_addr_r - $fdt_addr_r