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Paul Beesleyf3653a62019-05-22 11:22:44 +01001QEMU virt Armv8-A
2=================
Douglas Raillardd7c21b72017-06-28 15:23:03 +01003
Dan Handley610e7e12018-03-01 18:44:00 +00004Trusted Firmware-A (TF-A) implements the EL3 firmware layer for QEMU virt
5Armv8-A. BL1 is used as the BootROM, supplied with the -bios argument.
Douglas Raillardd7c21b72017-06-28 15:23:03 +01006When QEMU starts all CPUs are released simultaneously, BL1 selects a
7primary CPU to handle the boot and the secondaries are placed in a polling
8loop to be released by normal world via PSCI.
9
10BL2 edits the Flattened Device Tree, FDT, generated by QEMU at run-time to
11add a node describing PSCI and also enable methods for the CPUs.
12
Andrew Walbran9c4d0692020-01-15 14:11:31 +000013If ``ARM_LINUX_KERNEL_AS_BL33`` is set to 1 then this FDT will be passed to BL33
14via register x0, as expected by a Linux kernel. This allows a Linux kernel image
15to be booted directly as BL33 rather than using a bootloader.
16
Dan Handley610e7e12018-03-01 18:44:00 +000017An ARM64 defconfig v4.5 Linux kernel is known to boot, FDT doesn't need to be
Douglas Raillardd7c21b72017-06-28 15:23:03 +010018provided as it's generated by QEMU.
19
20Current limitations:
21
22- Only cold boot is supported
23- No build instructions for QEMU\_EFI.fd and rootfs-arm64.cpio.gz
24- No instructions for how to load a BL32 (Secure Payload)
25
26``QEMU_EFI.fd`` can be dowloaded from
27http://snapshots.linaro.org/components/kernel/leg-virt-tianocore-edk2-upstream/latest/QEMU-KERNEL-AARCH64/RELEASE_GCC49/QEMU_EFI.fd
28
29Boot binaries, except BL1, are primarily loaded via semi-hosting so all
30binaries has to reside in the same directory as QEMU is started from. This
31is conveniently achieved with symlinks the local names as:
32
33- ``bl2.bin`` -> BL2
34- ``bl31.bin`` -> BL31
35- ``bl33.bin`` -> BL33 (``QEMU_EFI.fd``)
36- ``Image`` -> linux/Image
37
38To build:
39
Paul Beesley493e3492019-03-13 15:11:04 +000040.. code:: shell
Douglas Raillardd7c21b72017-06-28 15:23:03 +010041
Paul Beesleyf3653a62019-05-22 11:22:44 +010042 make CROSS_COMPILE=aarch64-none-elf- PLAT=qemu
Douglas Raillardd7c21b72017-06-28 15:23:03 +010043
44To start (QEMU v2.6.0):
45
Paul Beesley493e3492019-03-13 15:11:04 +000046.. code:: shell
Douglas Raillardd7c21b72017-06-28 15:23:03 +010047
48 qemu-system-aarch64 -nographic -machine virt,secure=on -cpu cortex-a57 \
49 -kernel Image \
50 -append console=ttyAMA0,38400 keep_bootcon root=/dev/vda2 \
51 -initrd rootfs-arm64.cpio.gz -smp 2 -m 1024 -bios bl1.bin \
52 -d unimp -semihosting-config enable,target=native