12.3. TF-A CoT dt2c Tool
This tool is used to automatically generate the corresponding c file for a CoT DT file. Since currently TF-A support two type of CoT file: static c file and CoT DT binding. This is error prone and hard to maintain, therefore this tool can generate the c file for the platform that does not support CoT DT binding, given the CoT DT file so the c file can be deprecated.
12.3.1. Prerequisites
Python (3.8 or later)
Poetry Python package manager
12.3.2. Getting Started
cot-dt2c
is installed by default with TF-A’s poetry environment. All of it’s
dependencies are listed in tools/cot_dt2c/pyproject.toml.
cot-dt2c
requires a standard DTS file without #ifdef, macros, or other
preprocessor directives. Therefore, you need to provide a preprocessed device
tree source(DTS) as input to the tool.
Usage of the tool
cot-dt2c
This command will output the following as usage for this command
Usage: cot-dt2c [OPTIONS] COMMAND [ARGS]... Options: --version Show the version and exit. --help Show this message and exit. Commands: convert-to-c validate-cot visualize-cot validate-dt
12.3.3. Convert CoT descriptors to C file
To convert the CoT descriptors
This command is for the platform that does not use CoT DT parser, which can generate the C file given the CoT descriptors. Before the conversion to C file, the tool will do an implicit checks on the validity of the CoT DT file.
cot-dt2c convert-to-c [INPUT DTS PATH] [OUTPUT C PATH]
cot-dt2c convert-to-c fdts/tbbr_cot_descriptors.dtsi test.c
12.3.4. Validate CoT descriptors
To validate the certificate
The tests folder in the tool folder provides some bad-example of the DT file, and the tool will print out “not a valid CoT DT file” on console.
The command will check the format of the CoT file
The open bracket
The open ifdef macro
The missing mandatory attribute
Malformed DT file (cert missing parent, missing root certs. etc.)
Currently the validation is specifically for checking the CoT DT file
cot-dt2c validate-cot [INPUT DTS PATH]
cot-dt2c validate-cot fdts/tbbr_cot_descriptors.dtsi
12.3.5. Visualize CoT descriptors
This command create a HTML to visualize the relationship between the certificates and the image of a CoT DT file.
cot-dt2c visualize-cot [INPUT DTS PATH]
cot-dt2c visualize-cot fdts/tbbr_cot_descriptors.dtsi
12.3.6. Validate Other DT files
The command will transform the dtsi/dts file into a more standard dtsi/dts file inside /tmp folder that can be used as input to dt-schema for further validation. Currently the tool will perform some basic validation for the file (syntax) and dt-schema can be used for advance checks. dt-schema is not installed along with the tool.
cot-dt2c validate-dt [INPUT DTS PATH or INPUT DTS folder]
cot-dt2c validate-dt fdts/
cot-dt2c validate-dt fdts/fvp-bsae-gicv3.dtsi
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