notes.md

Notes

Notes, links and hints that helped me to develop the project.

QEMU

• Finding addresses of memory devices: info mtree
• virt source code

Syscalls / ecall

• Who provides syscalls in qemu-riscv?
• riscv-probe

Devices / drivers

UART / serial / chardev

• RISC-V NS16550A UART driver
• Chardev device options
• Try chardev: qemu-system-riscv64 -nographic -M virt -cpu rv64 -m 4G -smp $(QEMU_N_HARTS) -serial pty -bios opensbi/output/path/fw_payload.elf -device virtio-serial-device -chardev pty,id=serial3 -device virtconsole,chardev=serial3 -S -gdb tcp:localhost:9000

GoldfishRTC

• Memory: 0000000000101000-0000000000101023 (prio 0, i/o): goldfish_rt
• Goldfish docs
• Risc-V patch for qemu
• Implementationf of Goldfish in Linux
• Implementation of rtc_time64_to_tm

Linker

• setting initial value of __global_pointer$

Make

• A Simple Makefile Tutorial
• How patterns match
• Automatic variables

Minicom

• Connect via socket: minicom -D unix\#/tmp/xxx

C

• riscv-bare-metal - C and assembly files together
• div64 in mathlib linux

Assembly

• Compiler explorer - generates clean and readable assembly from various languages for various architectures. Brilliant!
• CFI directives in assemblyfiles