U-boot for arm64 Summary ======= No hardware platform of arm64 is available now. The u-boot is simulated on Foundation Model and Fast Model for ARMv8. Notes ===== 1. Currenly, u-boot run at the highest exception level processor supported and jump to EL2 or optionally EL1 before enter OS. 2. U-boot for arm64 is compiled with AArch64-gcc. AArch64-gcc use rela relocation format, a tool(tools/relocate-rela) by Scott Wood is used to encode the initial addend of rela to u-boot.bin. After running, the u-boot will be relocated to destination again. 3. Fdt should be placed at a 2-megabyte boundary and within the first 512 megabytes from the start of the kernel image. So, fdt_high should be defined specially. Please reference linux/Documentation/arm64/booting.txt for detail. 4. Spin-table is used to wake up secondary processors. One location (or per processor location) is defined to hold the kernel entry point for secondary processors. It must be ensured that the location is accessible and zero immediately after secondary processor enter slave_cpu branch execution in start.S. The location address is encoded in cpu node of DTS. Linux kernel store the entry point of secondary processors to it and send event to wakeup secondary processors. Please reference linux/Documentation/arm64/booting.txt for detail. 5. Generic board is supported. 6. CONFIG_ARM64 instead of CONFIG_ARMV8 is used to distinguish aarch64 and aarch32 specific codes. Contributor =========== Tom Rini Scott Wood York Sun Simon Glass Sharma Bhupesh Rob Herring