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ARM: Document AArch64 version of qemu-arm

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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>
This commit is contained in:
Tuomas Tynkkynen 2018-01-11 16:11:24 +02:00 committed by Tom Rini
parent ddcca73051
commit e7ba41c653
1 changed files with 16 additions and 5 deletions
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21
doc/README.qemu-arm
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@ -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: