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authorDavid Feng <fenghua@phytium.com.cn>2013-12-14 11:47:35 +0800
committerAlbert ARIBAUD <albert.u.boot@aribaud.net>2014-01-09 16:08:44 +0100
commit0ae7653128c80a4f2920cbe9b124792c2fd9d9e0 (patch)
tree14fea7a80e4ea84c7b6a3bc32298daeec55054c7 /doc/README.arm64
parent54799e4596bf8af33fd4a8dee153be7011c06d8d (diff)
arm64: core support
Relocation code based on a patch by Scott Wood, which is: Signed-off-by: Scott Wood <scottwood@freescale.com> Signed-off-by: David Feng <fenghua@phytium.com.cn>
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+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 <trini@ti.com>
+ Scott Wood <scottwood@freescale.com>
+ York Sun <yorksun@freescale.com>
+ Simon Glass <sjg@chromium.org>
+ Sharma Bhupesh <bhupesh.sharma@freescale.com>
+ Rob Herring <robherring2@gmail.com>