diff --git a/meta-arm-bsp/documentation/fvp-baser-aemv8r64.md b/meta-arm-bsp/documentation/fvp-baser-aemv8r64.md index fdf50387..1c723d9b 100644 --- a/meta-arm-bsp/documentation/fvp-baser-aemv8r64.md +++ b/meta-arm-bsp/documentation/fvp-baser-aemv8r64.md @@ -28,12 +28,65 @@ where either a standard or Real-Time Linux kernel (PREEMPT\_RT) can be built and run: - boot-wrapper-aarch64: provides PSCI support - - Linux kernel: linux-yocto-5.14 - - Linux kernel with PREEMPT\_RT support: linux-yocto-rt-5.14 + - U-Boot: v2022.01 - provides UEFI services + - Linux kernel: linux-yocto-5.15 + - Linux kernel with PREEMPT\_RT support: linux-yocto-rt-5.15 Note that the Real-Time Linux kernel (PREEMPT\_RT) does not use the real-time architectural extensions of the Armv8-R feature set. +High-Level Architecture +----------------------- + +The diagram below shows the current boot flow: + + +---------------------------------------------------------------+ + | Linux kernel | + +---------------------------------------------------------------+ + /|\ /|\ + | | + | UEFI services | + | PSCI services | + \|/ | + +----------------+ | S-EL1 + ----| U-Boot |------------------------------|----------- + +----------------+ | S-EL2 + /|\ | + | | + | | + | | + +--------------------------------------------------\|/----------+ + | +----------------+ +----------------+ | + | boot-wrapper-aarch64 | Device tree | | PSCI handler | | + | +----------------+ +----------------+ | + +---------------------------------------------------------------+ + + +The firmware binary (generated as `linux-system.axf`) includes +boot-wrapper-aarch64, the flattened device tree and U-Boot. U-Boot is configured +to automatically detect a virtio block device and boot the UEFI payload at the +path `/efi/boot/bootaa64.efi`. Using the standard build, the first partition +contains a Grub image at this path, which boots the Linux kernel at `/Image` on +the same partition. The second partition of the image contains the Linux root +file system. + +There is no EL3 or non-secure world in the Armv8-R AArch64 architecture, so the +reset vector starts boot-wrapper-aarch64 at S-EL2. Boot-wrapper-aarch64 is +compiled with the `--enable-keep-el` flag, which causes it to boot U-Boot at +S-EL2 too. U-Boot is compiled with the `CONFIG_ARMV8_SWITCH_TO_EL1` flag, which +causes it to switch to S-EL1 before booting Linux. + +The bundled device tree is passed to U-Boot via register x0. U-Boot passes the +same device tree to Linux via the UEFI system table. + +Power state management is provided by PSCI services in boot-wrapper-aarch64. +Linux accesses the PSCI handler via HVC calls to S-EL2. U-Boot has been patched +to prevent it from overriding the exception vector at S-EL2. The PSCI handler +memory region is added to a `/memreserve/` node in the device tree. + +Please note that the final firmware architecture for the fvp-baser-aemv8r64 is +not yet stabilized. The patches in this layer are provided for development and +evaluation purposes only, and should not be used in production firmware. Quick start: Howto Build and Run -------------------------------- @@ -167,6 +220,14 @@ Known Issues and Limitations Change Log ---------- +- Added U-Boot v2022.01 for UEFI support. +- Updated Linux kernel version from 5.14 to 5.15 for both standard and + Real-Time (PREEMPT\_RT) builds. +- Updated boot-wrapper-aarch64 revision and added support for booting U-Boot. +- Included boot-wrapper-aarch64 PSCI services in /memreserve/ region. +- Fixed the counter frequency initialization in boot-wrapper-aarch64. +- Configured the FVP to use the default RAM size of 4 Gb +- Fixed PL011 and SP805 register sizes in the device tree. - Added virtio_net User Networking mode by default and removed instructions about tap networking setup. - Updated Linux kernel version from 5.10 to 5.14 for both standard and