debug.md 1.1 KB
Debug
How to debug with QEMU + GDB?
This will only cover specifics, you have to know GDB debugging already.
First read the make debug target to get started. Those points will not be repeated here.
How to have debug symbols: http://stackoverflow.com/a/32960272/895245 TODO implement here. Needs to point GDB to an ELF file in addition to the remote listen.
How to step over int calls: http://stackoverflow.com/questions/24491516/how-to-step-over-interrupt-calls-when-debugging-a-bootloader-bios-with-gdb-and-q
Single stepping until a given opcode can be helpful sometimes: http://stackoverflow.com/a/31249378/895245
TODO: detect if we are on 16 or 32 bit automatically from control registers. Now I'm using 2 functions 16 and 32 to switch manually, but that sucks. The problem is that it's not possible to read them directly: http://stackoverflow.com/a/31340294/895245 If we had cr0, it would be easy to do with an if cr0 & 1 inside a hook-stop.
TODO: Take segmentation offsets into account: http://stackoverflow.com/questions/10354063/how-to-use-a-logical-address-in-gdb