1Allwinner ARMv8 SoCs 2==================== 3 4Trusted Firmware-A (TF-A) implements the EL3 firmware layer for Allwinner 5SoCs with ARMv8 cores. Only BL31 is used to provide proper EL3 setup and 6PSCI runtime services. 7 8U-Boot's SPL acts as a loader, loading both BL31 and BL33 (typically U-Boot). 9Loading is done from SD card, eMMC or SPI flash, also via an USB debug 10interface (FEL). 11 12BL31 lives in SRAM A2, which is documented to be accessible from secure 13world only. 14 15Current limitations: 16 17- Missing PMIC support 18 19After building bl31.bin, the binary must be fed to the U-Boot build system 20to include it in the FIT image that the SPL loader will process. 21bl31.bin can be either copied (or sym-linked) into U-Boot's root directory, 22or the environment variable BL31 must contain the binary's path. 23See the respective `U-Boot documentation`_ for more details. 24 25To build for machines with an A64 or H5 SoC: 26 27.. code:: shell 28 29 make CROSS_COMPILE=aarch64-linux-gnu- PLAT=sun50i_a64 DEBUG=1 bl31 30 31To build for machines with an H6 SoC: 32 33.. code:: shell 34 35 make CROSS_COMPILE=aarch64-linux-gnu- PLAT=sun50i_h6 DEBUG=1 bl31 36 37.. _U-Boot documentation: https://gitlab.denx.de/u-boot/u-boot/-/blob/master/board/sunxi/README.sunxi64 38 39Trusted OS dispatcher 40--------------------- 41 42One can boot Trusted OS(OP-TEE OS, bl32 image) along side bl31 image on Allwinner A64. 43 44In order to include the 'opteed' dispatcher in the image, pass 'SPD=opteed' on the command line 45while compiling the bl31 image and make sure the loader (SPL) loads the Trusted OS binary to 46the beginning of DRAM (0x40000000). 47