1U-boot for arm64 2 3Summary 4======= 5No hardware platform of arm64 is available now. The u-boot is 6simulated on Foundation Model and Fast Model for ARMv8. 7 8Notes 9===== 10 111. Currenly, u-boot run at the highest exception level processor 12 supported and jump to EL2 or optionally EL1 before enter OS. 13 142. U-boot for arm64 is compiled with AArch64-gcc. AArch64-gcc 15 use rela relocation format, a tool(tools/relocate-rela) by Scott Wood 16 is used to encode the initial addend of rela to u-boot.bin. After running, 17 the u-boot will be relocated to destination again. 18 193. Fdt should be placed at a 2-megabyte boundary and within the first 512 20 megabytes from the start of the kernel image. So, fdt_high should be 21 defined specially. 22 Please reference linux/Documentation/arm64/booting.txt for detail. 23 244. Spin-table is used to wake up secondary processors. One location 25 (or per processor location) is defined to hold the kernel entry point 26 for secondary processors. It must be ensured that the location is 27 accessible and zero immediately after secondary processor 28 enter slave_cpu branch execution in start.S. The location address 29 is encoded in cpu node of DTS. Linux kernel store the entry point 30 of secondary processors to it and send event to wakeup secondary 31 processors. 32 Please reference linux/Documentation/arm64/booting.txt for detail. 33 345. Generic board is supported. 35 366. CONFIG_ARM64 instead of CONFIG_ARMV8 is used to distinguish aarch64 and 37 aarch32 specific codes. 38 39Contributor 40=========== 41 Tom Rini <trini@ti.com> 42 Scott Wood <scottwood@freescale.com> 43 York Sun <yorksun@freescale.com> 44 Simon Glass <sjg@chromium.org> 45 Sharma Bhupesh <bhupesh.sharma@freescale.com> 46 Rob Herring <robherring2@gmail.com> 47