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. 38 397. CONFIG_SYS_FULL_VA is used to enable 2-level page tables. For cores 40 supporting 64k pages it allows usage of full 48+ virtual/physical addresses 41 42 Enabling this option requires the following ones to be defined: 43 - CONFIG_SYS_MEM_MAP - an array of 'struct mm_region' describing the 44 system memory map (start, length, attributes) 45 - CONFIG_SYS_MEM_MAP_SIZE - number of entries in CONFIG_SYS_MEM_MAP 46 - CONFIG_SYS_PTL1_ENTRIES - number of 1st level page table entries 47 - CONFIG_SYS_PTL2_ENTRIES - number of 1nd level page table entries 48 for the largest CONFIG_SYS_MEM_MAP entry 49 - CONFIG_COREID_MASK - the mask value used to get the core from the 50 MPIDR_EL1 register 51 - CONFIG_SYS_PTL2_BITS - number of bits addressed by the 2nd level 52 page tables 53 - CONFIG_SYS_BLOCK_SHIFT - number of bits addressed by a single block 54 entry from L2 page tables 55 - CONFIG_SYS_PGTABLE_SIZE - total size of the page table 56 - CONFIG_SYS_TCR_EL{1,2,3}_IPS_BITS - the IPS field of the TCR_EL{1,2,3} 57 58 59 60 61Contributor 62=========== 63 Tom Rini <trini@ti.com> 64 Scott Wood <scottwood@freescale.com> 65 York Sun <yorksun@freescale.com> 66 Simon Glass <sjg@chromium.org> 67 Sharma Bhupesh <bhupesh.sharma@freescale.com> 68 Rob Herring <robherring2@gmail.com> 69 Sergey Temerkhanov <s.temerkhanov@gmail.com> 70