Re: [Qemu-discuss] No start with -cpu option (was: Qemu-discuss Digest, Vol 95, Issue 8)

[Thomas]

Aug 13, 2019, 6:02 PM by address@hidden:

>>
>> Aug 7, 2019, 8:32 PM by address@hidden:
>>
>> >>
>> >> I'm definitetly not familiar with gdb debugging. But if someone is
>> >> interested in the problem and wants to be a tutor I'm up for the job.
>> >> I'm always up to learn something new.
>> >
>> https://wiki.qemu.org/Documentation/Platforms/PowerPC#Debugging_qemu-system-ppc_with_GDB_on_an_x86_Linux_host
>> > This information may help you.
>> >
>> Thanks, this helped a bit.
>>
>> Short version:
>> I found differences in the behaviour with or without -cpu 7447a_v1.2
>> option. It seems gdb can't debug with the cpu-option set. Commands like
>> 'backtrace' or 'where' did not finsh but had to be killed.
>>
>> Long version:
>> I started three terminals.
>>
>> Terminal 1:
>> | /usr/bin/qemu-system-ppc -machine mac99,via=pmu -m 512M -g 1280x854x32
>> -s -S -prom-env "auto-boot?=false" --nographic -monitor
>> "unix:sockets/ppcdebug",server,nowait -cpu 7447a_v1.2
>> | ##### There was no further output during the whole session
>> Terminal 2: # same output as before
>> | nc -U sockets/ppcdebug
>> | (qemu) info status
>> | info status
>> | VM status: paused (prelaunch)
>> | ##### after continuing in qemu:
>> | (qemu) info status| info status
>> | VM status: running
>> | ##### after CTRL-C in qemu
>> | (qemu) info status| info status
>> | VM status: paused
>>
>> Terminal 3:
>> | gdb-multiarch| (gdb) target remote localhost:1234| Remote debugging
>> using localhost:1234| warning: No executable has been specified and target
>> does not support| determining executable automatically.  Try using the
>> "file" command.| 0x0001f0ff in ?? ()| (gdb) show arch| The target
>> architecture is set automatically (currently powerpc:common)| (gdb)
>> continue| Continuing.
>> | ##### I waited about a minute
>> | ^C| Program received signal SIGINT, Interrupt.| 0x3cc9f2ff in ?? ()|
>> (gdb) where| ##### I waited about a minute
>> | ^CQuit| # I had to kill the where command - there was no output
>> I'm stuck. Which should be the next steps?
>> Thomas
>>
>
> I would print out the instructions that are executed:
>
> x/10i $pc
>

Hi!
Thanks!
I think qemu, OpenBios or something in between has taken the
wrong turn. There is no instruction at $pc.

| (gdb) continue
| Continuing.| ^C| Program received signal SIGINT, Interrupt.| 0x3cc9f2ff in ?? 
()| (gdb) x/10i $pc-20|    0x3cc9f2eb:  .long 0x0|    0x3cc9f2ef:       .long 
0x0|    0x3cc9f2f3:       .long 0x0|    0x3cc9f2f7:       .long 0x0|    
0x3cc9f2fb:       .long 0x0| => 0x3cc9f2ff:       .long 0x0|    0x3cc9f303:     
  .long 0x0|    0x3cc9f307:       .long 0x0|    0x3cc9f30b:       .long 0x0|    
0x3cc9f30f:       .long 0x0| (gdb)

Thomas