This is an experimental library that aims to provide debugger support for seL4 based systems. It is being developed primarily for use with the seL4 microkit but has been implemented as a library that can be used on other seL4-based systems. It has been tested most on the odroidc2 platform but has also been used on odroidc4 and qemu-arm-virt, and should work with any other aarch64 platform.
The library is generally used in combination with a debugger component, which has holds thread control block (TCB) and VSpace capabilities of the threads which are to be debugged. It is also expected to be the fault handler for these threads. The main responsibilities of the debugger component are to initialize the state in libGDB by registering inferiors, handle communication between the host machine (running GDB) and libGDB, and pass along faults to the library.
This repository contains two examples - microkit_sddf_serial and microkit_integrated_serial.
These two examples show different ways that a debugger can be implemented. microkit_integrated_serial
uses an internal polling UART driver for input whereas microkit_sddf_serial is sDDF-compliant and
contains an sDDF subsystem with a separate UART driver as well as recieve and transmit virtualisers.
This library depends on seL4 and microkit changes that have not yet been upstreamed. As such, a custom version of the microkit will have to be built using the following sources.
microkit: https://github.com/alwin-joshy/microkit/tree/dev_gdb
seL4: https://github.com/alwin-joshy/seL4/tree/microkit_gdb_final
The examples depend on the aarch64-none-elf toolchain for compilation, and libGDB has only been tested with aarch64-none-elf-gdb,
though any GDB that has architecture support for aarch64 should suffice.
The serial-demux tool depends on the Rust toolchain.
NOTE: These kernel and microkit changes may break other configurations. Use at your own risk.
We provide both a CMakeLists.txt and libgdb.mk Makefile snippet. To see how either can be
used, look at the microkit_integrated_serial and microkit_sddf_serial examples respectively.
As mentioned before, libGDB was primarily designed for use with the seL4 Microkit, but should be simple to port to other frameworks. It currently depends on Microkit for seL4-related infomation.