QEMU Monitor Cheat Sheet

• Start the monitor with Ctrl + A then C
• Exit QEMU by using q in the monitor
• Use info registers to view CPU regs
• Use stop and cont to control execution

OpenSBI Calls

NOTE

unimp is a "pseudo" instruction.

According to RISC-V Assembly Programmer's Manual, the assembler translates unimp to the following instruction:

csrrw x0, cycle, x0

This reads and writes the cycle register into x0. Since cycle is a read-only register, CPU determines that the instruction is invalid and triggers an illegal instruction exception.

Current Status

Reached Here

Run with GDB

qemu-system-riscv64 -machine virt -bios default -nographic -serial mon:stdio --no-reboot -gdb tcp::1234 -S -kernel kernel.elf