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user/aarch64/raspberrypi4: Boot mechanism explained and updated config.txt

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Mohd Noor Aman 2022-10-08 22:49:40 +05:30 committed by Joel Sherrill
parent fe10830f24
commit f13489efb4
1 changed files with 11 additions and 4 deletions
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15
user/bsps/aarch64/raspberrypi4.rst
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@ -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=<img_name>`` 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
<https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#boot-sequence>`_.
By default the arm64 mode looks for the ``kernel8.img``. Any other kernel can be
loaded by adding ``kernel=<img_name>`` 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