ARM: Document AArch64 version of qemu-arm
It's mostly obvious, except that QEMU is annoying and requires an
explicit '-cpu cortex-a57' (or some other 64-bit core) to actually run
in 64-bit mode.
While at it, remove the references to setting the ARCH environment
variable; that is not used in U-Boot.
Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/doc/README.qemu-arm b/doc/README.qemu-arm
index 2895e3b..aee7894 100644
--- a/doc/README.qemu-arm
+++ b/doc/README.qemu-arm
@@ -4,11 +4,12 @@
# SPDX-License-Identifier: GPL-2.0+
#
-U-Boot on QEMU's 'virt' machine on ARM
-======================================
+U-Boot on QEMU's 'virt' machine on ARM & AArch64
+================================================
QEMU for ARM supports a special 'virt' machine designed for emulation and
virtualization purposes. This document describes how to run U-Boot under it.
+Both 32-bit ARM and AArch64 are supported.
The 'virt' platform provides the following as the basic functionality:
@@ -17,7 +18,7 @@
- A generated device tree blob placed at the start of RAM
- A freely configurable amount of RAM, described by the DTB
- A PL011 serial port, discoverable via the DTB
- - An ARMv7 architected timer
+ - An ARMv7/ARMv8 architected timer
- PSCI for rebooting the system
- A generic ECAM-based PCI host controller, discoverable via the DTB
@@ -25,19 +26,29 @@
Building U-Boot
---------------
-Set the CROSS_COMPILE and ARCH=arm environment variables as usual, and run:
+Set the CROSS_COMPILE environment variable as usual, and run:
+- For ARM:
make qemu_arm_defconfig
make
+- For AArch64:
+ make qemu_arm64_defconfig
+ make
+
Running U-Boot
--------------
The minimal QEMU command line to get U-Boot up and running is:
+- For ARM:
qemu-system-arm -machine virt,highmem=off -bios u-boot.bin
+- For AArch64:
+ qemu-system-aarch64 -machine virt,highmem=off -cpu cortex-a57 -bios u-boot.bin
+
The 'highmem=off' parameter to the 'virt' machine is required for PCI to work
-in U-Boot.
+in U-Boot. Also, for some odd reason qemu-system-aarch64 needs to be explicitly
+told to use a 64-bit CPU or it will boot in 32-bit mode.
Additional peripherals that have been tested to work in both U-Boot and Linux
can be enabled with the following command line parameters: