rpi2 usb boot
Posted: Thu Oct 31, 2019 8:37 am
I know, I know... I'm not trolling (in a sense...) let's get to work!!!
The Idea here is to boot from SD card, load uboot and link/tag usb boot partition to continue boot the Pi. This is the only way in order to boot from external usb hard drive the pi.
first of all I gathered info from these sources:
[*]setting up U-Boot into SD:
https://blog.christophersmart.com/2016/ ... rm-boards/
1. I used VirtualBox in my Arch system and installed Fedora for my guest Os
2. I connected my usb/card reader and passed-through my Fedora guest
Partition the SD card
you don't need ext4 partition because you'll use that from USB!!
Assuming your card is at /dev/sdx (replace as necessary, check dmesg after plugging it in if you’re not sure).
Now we can format the partitions (upstream U-Boot supports ext3 on the boot partition).
Next, mount the boot partition to /mnt, this is where we will copy everything to.
Upstream U-Boot Bootloader
We need to clone upstream U-Boot Git tree. Note that I’m checking out the release directly (-b v2019.10) but you could leave this off to get master, or change it to a different tag if you want.
There are default configs for both Raspberry Pi 2 and 3, so select the one you want.
# Run this for the Pi 2
# Run this for the Pi 3
Now, compile it.
Now, copy the u-boot.bin file onto the SD card, and call it kernel.img (this is what the bootloader looks for).
Proprietary bootloader files
Sadly, the Raspberry Pi cannot boot entirely on open source software, we need to get the proprietary files from Broadcom and place them on the SD card also.
Clone the Raspberry Pi Foundation’s GitHub repository.
Copy the minimum set of required files to the SD card.
Finally, unmount the SD card.
OK, now our bootloader should be ready to go.
Bootloader config
Next we need to make a bootloader file, boot.cmd, which tells U-Boot what to load and boot (the kernel, device tree and initramfs).
The bootargs line says to output the console to serial and to boot from the ramdisk. Variables are used for the memory locations of the kernel, dtb and initramfs.
Note that the root device is /dev/root which is required for the initramfs.
Compile the bootloader file and output it directly to the SD card at /mnt.
Now, unmount your SD card.
Prepare Usb Disk
I used ArchLinuxArm and followed those instructions. make sure you put boot partition in the 1st place and root 2nd.
After Booting Arch Linux
finalizing Arch with this tutorial:
https://github.com/phortx/Raspberry-Pi-Setup-Guide
Final Words
this guide is for those who want pure usb bootable system from RPI that supports U-Boot and doesn't support usb from start... I was playing with my RPI2 and all I've ever wanted was to update my system and to minimize sd card corruption/degradation from the read/write jobs.
inside my boot.cmd file I linked some files from my USB boot partition that comes with Arch-Arm Image preinstalled
1. /kernel7.img
2. /${fdtfile}
3. /initramfs-linux.img
all 3 of them are located inside my usb boot partition
an image after booting rpi2:
The Idea here is to boot from SD card, load uboot and link/tag usb boot partition to continue boot the Pi. This is the only way in order to boot from external usb hard drive the pi.
first of all I gathered info from these sources:
[*]setting up U-Boot into SD:
https://blog.christophersmart.com/2016/ ... rm-boards/
1. I used VirtualBox in my Arch system and installed Fedora for my guest Os
2. I connected my usb/card reader and passed-through my Fedora guest
Partition the SD card
you don't need ext4 partition because you'll use that from USB!!
Assuming your card is at /dev/sdx (replace as necessary, check dmesg after plugging it in if you’re not sure).
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sudo umount /dev/sdx* # makes sure it's not mounted
sudo parted -s /dev/sdx \
mklabel msdos \
mkpart primary fat32 1M 30M
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sudo mkfs.vfat /dev/sdx1
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sudo mount /dev/sdx1 /mnt
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sudo dnf install \
gcc-arm-linux-gnu \
binutils-arm-linux-gnu \
uboot-tools
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cd "${HOME}"
git clone --depth 1 -b v2019.10 git://git.denx.de/u-boot.git
cd u-boot
# Run this for the Pi 2
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CROSS_COMPILE=arm-linux-gnu- make rpi_2_defconfig
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CROSS_COMPILE=arm-linux-gnu- make rpi_3_32b_defconfig
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CROSS_COMPILE=arm-linux-gnu- make -j$(nproc)
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sudo cp -iv u-boot.bin /mnt/kernel.img
Sadly, the Raspberry Pi cannot boot entirely on open source software, we need to get the proprietary files from Broadcom and place them on the SD card also.
Clone the Raspberry Pi Foundation’s GitHub repository.
Code: Select all
cd "${HOME}"
git clone --depth 1 https://github.com/raspberrypi/firmware
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sudo cp -iv firmware/boot/{bootcode.bin,fixup.dat,start.elf} /mnt/
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sync && sudo umount /mnt
Bootloader config
Next we need to make a bootloader file, boot.cmd, which tells U-Boot what to load and boot (the kernel, device tree and initramfs).
The bootargs line says to output the console to serial and to boot from the ramdisk. Variables are used for the memory locations of the kernel, dtb and initramfs.
Note that the root device is /dev/root which is required for the initramfs.
Code: Select all
cat > boot.cmd << EOF
# After modifying, run ./mkscr
#Set root partition to the second partition of boot device
setenv usb_pgood_delay 10000; #usb_pgood_delay initial value was 2000 and the usb search inside uboot was failing
setenv fdtfile bcm2709-rpi-2-b.dtb #load from sd card the dev tree
usb stop;
usb start;
usb dev 0;
setenv bootargs console=ttyS1,115200 console=tty0 root=/dev/sda2 rw rootwait rootdelay=30 smsc95xx.macaddr="${usbethadd>
if load usb 0:1 ${kernel_addr_r} /kernel7.img; then
if load usb 0:1 ${fdt_addr_r} /${fdtfile}; then
if load usb 0:1 ${ramdisk_addr_r} /initramfs-linux.img; then
setenv usb_pgood_delay 200; #reset the value here because the 1st usb search always fails
bootz ${kernel_addr_r} ${ramdisk_addr_r}:${filesize} ${fdt_addr_r};
else
setenv usb_pgood_delay 200; #reset the value here because the 1st usb search always fails
bootz ${kernel_addr_r} - ${fdt_addr_r};
fi;
fi;
fi
EOF
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sudo mkimage -C none -A arm -T script -d boot.cmd /mnt/boot.scr
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sudo umount /dev/sdx*
I used ArchLinuxArm and followed those instructions. make sure you put boot partition in the 1st place and root 2nd.
After Booting Arch Linux
finalizing Arch with this tutorial:
https://github.com/phortx/Raspberry-Pi-Setup-Guide
Final Words
this guide is for those who want pure usb bootable system from RPI that supports U-Boot and doesn't support usb from start... I was playing with my RPI2 and all I've ever wanted was to update my system and to minimize sd card corruption/degradation from the read/write jobs.
inside my boot.cmd file I linked some files from my USB boot partition that comes with Arch-Arm Image preinstalled
1. /kernel7.img
2. /${fdtfile}
3. /initramfs-linux.img
all 3 of them are located inside my usb boot partition
an image after booting rpi2:
