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 --- v2: Drop ARCH=arm as it turns out not to be needed in U-Boot. --- doc/README.qemu-arm | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-)
diff --git a/doc/README.qemu-arm b/doc/README.qemu-arm index 2895e3b97f..aee789447a 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 @@ The 'virt' platform provides the following as the basic functionality: - 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 @@ Additionally, a number of optional peripherals can be added to the PCI bus.
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: