BeagleV
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=======
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BeagleV is a low-cost RISC-V 64-bit based platform, powered by a
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Starfive JH7100 processor. The current defconfig in Buildroot has been
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tested with the JH7100 chip used on the beta version of the BeagleV
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board.
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How to build
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============
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$ make beaglev_defconfig
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$ make
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Build results
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=============
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After building, output/images contains:
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+ bootloader-BEAGLEV-buildroot.bin.out
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+ ddrinit-2133-buildroot.bin.out
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+ Image
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+ fw_payload.bin
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+ fw_payload.bin.out
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+ fw_payload.elf
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+ rootfs.ext2
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+ rootfs.ext4
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+ sdcard.img
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+ u-boot.bin
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The four important files are:
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- bootloader-BEAGLEV-buildroot.bin.out, the first stage bootloader
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- ddrinit-2133-buildroot.bin.out, the DDR initialization firmware
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- fw_payload.bin.out, which is the bootloader image, containing
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both OpenSBI and U-Boot.
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- sdcard.img, the SD card image, which contains the root filesystem,
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kernel image and Device Tree.
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Flashing the SD card image
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==========================
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$ sudo dd if=output/images/sdcard.img of=/dev/sdX
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Preparing the board
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===================
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Connect the Beagle-V fan to the 5V supply (pin 2 or 4 of the GPIO
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connector) and GND (pin 6 of the GPIO connector).
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Connect a TTL UART cable to pin 8 (TX), 10 (RX) and 14 (GND).
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Insert your SD card.
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Power-up the board using an USB-C cable.
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Flashing OpenSBI/U-Boot
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=======================
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The bootloader pre-flashed on the Beagle-V has a non-working
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fdt_addr_r environment variable value, so it won't work
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as-is. Reflashing the bootloader with the bootloader image produced by
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Buildroot is necessary.
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When the board starts up, a pre-loader shows a count down of 2
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seconds, interrupt by pressing any key. You should reach a menu like
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this:
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--------8<----------
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bootloader version:210209-4547a8d
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ddr 0x00000000, 1M test
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ddr 0x00100000, 2M test
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DDR clk 2133M,Version: 210302-5aea32f
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0
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***************************************************
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*************** FLASH PROGRAMMING *****************
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***************************************************
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0:update uboot
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1:quit
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select the function:
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--------8<----------
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Press 0 and Enter. You will now see "C" characters being
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displayed. Ask your serial port communication program to send
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fw_payload.bin.out using the Xmodem protocol.
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After reflashing is complete, restart the board, it will automatically
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start the system from the SD card, and reach the login prompt.
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Flashing low-level bootloaders
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==============================
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The BeagleV comes pre-flashed with functional low-level bootloaders
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(called "secondboot" and "ddrinit"). Re-flashing them is not necessary
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to use this Buildroot defconfig. However, for the sake of
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completeness, Buildroot builds and provides those low-level bootloader
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images.
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You can flash them as follows:
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- In the same "pre-loader" menu as the one used above, instead of
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entering 0 or 1, enter the magic "root@s5t" string. This enters the
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"expert" features.
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- Then, press 0 and send over X-modem the
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bootloader-BEAGLEV-buildroot.bin.out file.
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- Then, press 1 and send over X-modem the
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ddrinit-2133-buildroot.bin.out.
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Note that the reflashing mechanism itself relies on those low-level
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bootloaders, so if you flash non-working versions, you'll have to go
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through a recovery process. This requires wiring up to a separate
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debug UART, which pins are located near the HDMI connector. See
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https://wiki.seeedstudio.com/BeagleV-Update-bootloader-ddr-init-boot-uboot-Recover-bootloader/
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section "Recover the bootloader" for more details. The instructions
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make use of a jh7100-recover tool, which Buildroot has built as part
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of this defconfig: it is available as output/host/bin/jh7100-recover.
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