Makefile: drop unused cpp_cfg macro

[u-boot] / doc / README.arm64

diff --git a/doc/README.arm64 b/doc/README.arm64
index 75586dbaa703779e055e042c093837693658b8f0..b0bba0fc65e4634c602fdab7627e0d7b4ba4758f 100644 (file)
--- a/doc/README.arm64
+++ b/doc/README.arm64
@@ -1,24 +1,32 @@
-U-boot for arm64
+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.
+The initial arm64 U-Boot port was developed before hardware was available,
+so the first supported platforms were the Foundation and Fast Model for ARMv8.
+These days U-Boot runs on a variety of 64-bit capable ARM hardware, from
+embedded development boards to servers.
 
 Notes
 =====
 
-1. Currenly, u-boot run at the highest exception level processor
-   supported and jump to EL2 or optionally EL1 before enter OS.
+1. U-Boot can run at any exception level it is entered in, it is
+   recommened to enter it in EL3 if U-Boot takes some responsibilities of a
+   classical firmware (like initial hardware setup, CPU errata workarounds
+   or SMP bringup). U-Boot can be entered in EL2 when its main purpose is
+   that of a boot loader. It can drop to lower exception levels before
+   entering the OS.
 
-2. U-boot for arm64 is compiled with AArch64-gcc. AArch64-gcc
+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.
+   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.
+3. Earlier Linux kernel versions required the FDT to be placed at a
+   2 MB boundary and within the same 512 MB section as the kernel image,
+   resulting in fdt_high to be defined specially.
+   Since kernel version 4.2 Linux is more relaxed about the DT location, so it
+   can be placed anywhere in memory.
    Please reference linux/Documentation/arm64/booting.txt for detail.
 
 4. Spin-table is used to wake up secondary processors. One location
@@ -36,11 +44,13 @@ Notes
 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>
+
+Contributors
+============
+   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>
+   Sergey Temerkhanov  <s.temerkhanov@gmail.com>