1Trusted Firmware-A for Allwinner 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. 7U-Boot's SPL acts as a loader, loading both BL31 and BL33 (typically U-Boot). 8Loading is done from SD card, eMMC or SPI flash, also via an USB debug 9interface (FEL). 10BL31 lives in SRAM A2, which is documented to be accessible from secure 11world only. 12 13Current limitations: 14 15- Missing PMIC support 16 17After building bl31.bin, the binary must be fed to the U-Boot build system 18to include it in the FIT image that the SPL loader will process. 19bl31.bin can be either copied (or sym-linked) into U-Boot's root directory, 20or the environment variable BL31 must contain the binary's path. 21See the respective `U-Boot documentation`_ for more details. 22 23To build: 24 25:: 26 27 make CROSS_COMPILE=aarch64-linux-gnu- PLAT=sun50i_a64 DEBUG=1 bl31 28 29.. _U-Boot documentation: http://git.denx.de/?p=u-boot.git;f=board/sunxi/README.sunxi64;hb=HEAD 30