From f13489efb43ddafc96ee63e240e68e0253d8ef02 Mon Sep 17 00:00:00 2001 From: Mohd Noor Aman Date: Sat, 8 Oct 2022 22:49:40 +0530 Subject: user/aarch64/raspberrypi4: Boot mechanism explained and updated config.txt --- user/bsps/aarch64/raspberrypi4.rst | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) (limited to 'user/bsps') diff --git a/user/bsps/aarch64/raspberrypi4.rst b/user/bsps/aarch64/raspberrypi4.rst index 729d71b..efb09b6 100644 --- a/user/bsps/aarch64/raspberrypi4.rst +++ b/user/bsps/aarch64/raspberrypi4.rst @@ -34,10 +34,14 @@ raspberrypi hardware. Mini-uart is not supported. Preparing to boot ------------------ -Raspberry Pi uses a different mechanism to boot. First the GPU initializes, -loads the bootloader and then looks for the kernel img. By default the arm64 -mode looks for the ``kernel8.img``. Any other kernel can be loaded by adding -``kernel=`` to the ``config.txt`` file. +Raspberry Pi uses a different mechanism to boot when compared with any ARM SoC. +First the GPU initializes, loads the bootloader (Raspberry pi firmware) and then +looks for the kernel img. This whole process is done by the GPU (VideoCore IV) +till the kernel is loaded. More information can be found on the `Raspberry pi +documentation page +`_. +By default the arm64 mode looks for the ``kernel8.img``. Any other kernel can be +loaded by adding ``kernel=`` to the ``config.txt`` file. The Firmware files are required in order to boot RTEMS. The latest firmware can be downloaded from the `Raspberry Pi Firmware Repository @@ -56,6 +60,9 @@ default Mini-uart. .. code-block:: none + # if user wants to enable GIC, uncomment the next line + # enable_gic=1 + arm_64bit=1 dtoverlay = disable-bt enable_uart=1 -- cgit v1.2.3