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Correct spelling of "U-Boot" shall be used in all written text (documentation, comments in source files etc.). Signed-off-by: Bin Meng <bmeng.cn@gmail.com> Reviewed-by: Heiko Schocher <hs@denx.de> Reviewed-by: Simon Glass <sjg@chromium.org> Reviewed-by: Minkyu Kang <mk7.kang@samsung.com>
70 lines
2.9 KiB
Plaintext
70 lines
2.9 KiB
Plaintext
U-Boot for arm64
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Summary
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=======
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No hardware platform of arm64 is available now. The U-Boot is
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simulated on Foundation Model and Fast Model for ARMv8.
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Notes
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=====
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1. Currenly, U-Boot run at the highest exception level processor
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supported and jump to EL2 or optionally EL1 before enter OS.
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2. U-Boot for arm64 is compiled with AArch64-gcc. AArch64-gcc
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use rela relocation format, a tool(tools/relocate-rela) by Scott Wood
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is used to encode the initial addend of rela to u-boot.bin. After running,
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the U-Boot will be relocated to destination again.
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3. Fdt should be placed at a 2-megabyte boundary and within the first 512
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megabytes from the start of the kernel image. So, fdt_high should be
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defined specially.
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Please reference linux/Documentation/arm64/booting.txt for detail.
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4. Spin-table is used to wake up secondary processors. One location
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(or per processor location) is defined to hold the kernel entry point
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for secondary processors. It must be ensured that the location is
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accessible and zero immediately after secondary processor
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enter slave_cpu branch execution in start.S. The location address
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is encoded in cpu node of DTS. Linux kernel store the entry point
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of secondary processors to it and send event to wakeup secondary
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processors.
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Please reference linux/Documentation/arm64/booting.txt for detail.
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5. Generic board is supported.
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6. CONFIG_ARM64 instead of CONFIG_ARMV8 is used to distinguish aarch64 and
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aarch32 specific codes.
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7. CONFIG_SYS_FULL_VA is used to enable 2-level page tables. For cores
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supporting 64k pages it allows usage of full 48+ virtual/physical addresses
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Enabling this option requires the following ones to be defined:
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- CONFIG_SYS_MEM_MAP - an array of 'struct mm_region' describing the
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system memory map (start, length, attributes)
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- CONFIG_SYS_MEM_MAP_SIZE - number of entries in CONFIG_SYS_MEM_MAP
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- CONFIG_SYS_PTL1_ENTRIES - number of 1st level page table entries
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- CONFIG_SYS_PTL2_ENTRIES - number of 1nd level page table entries
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for the largest CONFIG_SYS_MEM_MAP entry
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- CONFIG_COREID_MASK - the mask value used to get the core from the
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MPIDR_EL1 register
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- CONFIG_SYS_PTL2_BITS - number of bits addressed by the 2nd level
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page tables
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- CONFIG_SYS_BLOCK_SHIFT - number of bits addressed by a single block
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entry from L2 page tables
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- CONFIG_SYS_PGTABLE_SIZE - total size of the page table
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- CONFIG_SYS_TCR_EL{1,2,3}_IPS_BITS - the IPS field of the TCR_EL{1,2,3}
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Contributor
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===========
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Tom Rini <trini@ti.com>
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Scott Wood <scottwood@freescale.com>
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York Sun <yorksun@freescale.com>
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Simon Glass <sjg@chromium.org>
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Sharma Bhupesh <bhupesh.sharma@freescale.com>
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Rob Herring <robherring2@gmail.com>
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Sergey Temerkhanov <s.temerkhanov@gmail.com>
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