Testing with Bochs

• Bochs is a cross-platform open-source x86_64 PC emulator
  • Extremely helpful in an early-phase of hypervisor development
  • Capable of emulating both VMX and SVM, even on ARM-based systems
  • Most importantly, you can debug failure of an instruction
    • for example, error log on the failure of VMLAUNCH

      [CPU0  ]e| VMFAIL: VMCS host state invalid CR0 0x00000000
      

  • Built-in debugger
    • GUI (Windows-only)
    • CLI

      h|help - show list of debugger commands
      h|help command - show short command description
      -*- Debugger control -*-
          help, q|quit|exit, set, instrument, show, trace, trace-reg,
          trace-mem, u|disasm, ldsym, slist, addlyt, remlyt, lyt, source
      -*- Execution control -*-
          c|cont|continue, s|step, p|n|next, modebp, vmexitbp
      -*- Breakpoint management -*-
          vb|vbreak, lb|lbreak, pb|pbreak|b|break, sb, sba, blist,
          bpe, bpd, d|del|delete, watch, unwatch
      -*- CPU and memory contents -*-
          x, xp, setpmem, writemem, loadmem, crc, info, deref,
          r|reg|regs|registers, fp|fpu, mmx, sse, sreg, dreg, creg,
          page, set, ptime, print-stack, bt, print-string, ?|calc
      -*- Working with bochs param tree -*-
          show "param", restore
      

• Good idea to start with Bochs, then VMware. Last but not least, bare metal