19. QEMU virt Armv8-A

Trusted Firmware-A (TF-A) implements the EL3 firmware layer for QEMU virt Armv8-A. BL1 is used as the BootROM, supplied with the -bios argument. When QEMU starts all CPUs are released simultaneously, BL1 selects a primary CPU to handle the boot and the secondaries are placed in a polling loop to be released by normal world via PSCI.

BL2 edits the Flattened Device Tree, FDT, generated by QEMU at run-time to add a node describing PSCI and also enable methods for the CPUs.

If ARM_LINUX_KERNEL_AS_BL33 is set to 1 then this FDT will be passed to BL33 via register x0, as expected by a Linux kernel. This allows a Linux kernel image to be booted directly as BL33 rather than using a bootloader.

An ARM64 defconfig v5.5 Linux kernel is known to boot, FDT doesn’t need to be provided as it’s generated by QEMU.

Current limitations:

  • Only cold boot is supported

  • No build instructions for QEMU_EFI.fd and rootfs-arm64.cpio.gz

QEMU_EFI.fd can be dowloaded from http://snapshots.linaro.org/components/kernel/leg-virt-tianocore-edk2-upstream/latest/QEMU-KERNEL-AARCH64/RELEASE_GCC5/QEMU_EFI.fd

19.1. Booting via semi-hosting option

Boot binaries, except BL1, are primarily loaded via semi-hosting so all binaries has to reside in the same directory as QEMU is started from. This is conveniently achieved with symlinks the local names as:

  • bl2.bin -> BL2

  • bl31.bin -> BL31

  • bl33.bin -> BL33 (QEMU_EFI.fd)

  • Image -> linux/arch/arm64/boot/Image

To build:

make CROSS_COMPILE=aarch64-none-elf- PLAT=qemu

To start (QEMU v4.1.0):

qemu-system-aarch64 -nographic -machine virt,secure=on -cpu cortex-a57  \
    -kernel Image                           \
    -append "console=ttyAMA0,38400 keep_bootcon root=/dev/vda2"   \
    -initrd rootfs-arm64.cpio.gz -smp 2 -m 1024 -bios bl1.bin   \
    -d unimp -semihosting-config enable,target=native

19.2. Booting via flash based firmwares

Boot firmwares are loaded via secure FLASH0 device so bl1.bin and fip.bin should be concatenated to create a flash.bin that is flashed onto secure FLASH0.

  • bl32.bin -> BL32 (tee-header_v2.bin)

  • bl32_extra1.bin -> BL32 Extra1 (tee-pager_v2.bin)

  • bl32_extra2.bin -> BL32 Extra2 (tee-pageable_v2.bin)

  • bl33.bin -> BL33 (QEMU_EFI.fd)

  • Image -> linux/arch/arm64/boot/Image

To build:

make CROSS_COMPILE=aarch64-linux-gnu- PLAT=qemu BL32=bl32.bin \
    BL32_EXTRA1=bl32_extra1.bin BL32_EXTRA2=bl32_extra2.bin \
    BL33=bl33.bin BL32_RAM_LOCATION=tdram SPD=opteed all fip

To build with TBBR enabled, BL31 and BL32 encrypted with test key:

make CROSS_COMPILE=aarch64-linux-gnu- PLAT=qemu BL32=bl32.bin \
    BL32_EXTRA1=bl32_extra1.bin BL32_EXTRA2=bl32_extra2.bin \
    BL33=bl33.bin BL32_RAM_LOCATION=tdram SPD=opteed all fip \
    MBEDTLS_DIR=<path-to-mbedtls-repo> TRUSTED_BOARD_BOOT=1 \
    GENERATE_COT=1 DECRYPTION_SUPPORT=aes_gcm FW_ENC_STATUS=0 \
    ENCRYPT_BL31=1 ENCRYPT_BL32=1

To build flash.bin:

dd if=build/qemu/release/bl1.bin of=flash.bin bs=4096 conv=notrunc
dd if=build/qemu/release/fip.bin of=flash.bin seek=64 bs=4096 conv=notrunc

To start (QEMU v2.6.0):

qemu-system-aarch64 -nographic -machine virt,secure=on -cpu cortex-a57  \
    -kernel Image -no-acpi                     \
    -append 'console=ttyAMA0,38400 keep_bootcon root=/dev/vda2'  \
    -initrd rootfs-arm64.cpio.gz -smp 2 -m 1024 -bios flash.bin   \
    -d unimp