Virtualization on Renesas R-Car Platforms
- QEMU (e.g. "apt-get install qemu-system-arm"),
- A guest image, e.g. "openwrt-arm64-qemu-virt.Image" from OpenWRT.
$ qemu-system-aarch64 -m 1024 -cpu cortex-a57 -M virt -nographic -kernel openwrt-arm64-qemu-virt.Image
and press <ENTER> to enjoy your new ARM64 system!
Recent kernels may access ARM64 registers that require a recent version of QEMU. If your kernel crashes with
Code: ........ ........ ........ ........ (d5380740) Internal error: undefined instruction: 0 [#1] SMP ... pc : __cpuinfo_store_cpu+0x68/0x1b0
you have to upgrade QEMU, or comment out the following two lines in arch/arm64/kernel/cpuinfo.c:__cpuinfo_store_cpu():
info->reg_id_aa64mmfr2 = read_cpuid(ID_AA64MMFR2_EL1); info->reg_id_aa64zfr0 = read_cpuid(ID_AA64ZFR0_EL1);
When using an arm64 platform as the host system, guest performance can be improved drastically by making use of the Kernel-based Virtual Machine (KVM).
Host Kernel Configuration
Make sure your host kernel has the following options enabled:
"renesas_defconfig" should be fine.
To use KVM, the firmware on your board must start Linux in hypervisor (EL2 / HYP) mode.
If your host kernel prints:
CPU: All CPU(s) started at EL2 ... kvm : Hyp mode initialized successfully
during boot up, everything is fine, and you can skip the next section.
If your host kernel prints:
CPU: All CPU(s) started at EL1 ... kvm : HYP mode not available
during bootup, HYP mode is not available, and KVM cannot be used, unless you first replace the firmware of your board with a version that supports HYP mode.
Enabling HYP Support
To build your own ARM Trusted Firmware with hypervisor mode support:
$ git clone email@example.com:renesas-rcar/arm-trusted-firmware.git $ cd arm-trusted-firmware $ make CROSS_COMPILE=aarch64-linux-gnu- PLAT=rcar RCAR_DRAM_SPLIT=3 RCAR_BL33_EXECUTION_EL=1 LSI=H3 # or LSI=M3
Replace the BL2 and BL31 binaries in your firmware package by the generated "build/rcar/release/bl2.srec" and "build/rcar/release/bl31.srec", and follow your normal firmware upgrade procedure.
Running QEMU with KVM
$ qemu-system-aarch64 -enable-kvm -m 1024 -cpu cortex-a57 -M virt -nographic -kernel openwrt-arm64-qemu-virt.Image
and press <ENTER> to enjoy a faster new ARM64 system!
Note that the above command requires running on a Cortex-A57 CPU core. When running on a Cortex-A53 CPU core in a big.LITTLE configuration, the command will fail with:
kvm_init_vcpu failed: Invalid argument
Just retry, or force your luck by disabling all Cortex-A53 cores:
echo 0 > /sys/devices/system/cpu/cpuN/online
for all "cpuN" representing Cortex-A53 cores.
Building your own guest kernel
The kernel config file used for the OpenWRT guest image is a good starting point. You can extract it from '/proc/config.gz' on the running system.
You can extract the initramfs from an OpenWRT guest image using 'binwalk'. Make sure to truncate the initramfs file after the first 256-byte boundary after "TRAILER!!!", else the kernel with crash with
Kernel panic - not syncing: broken padding