Re: [Qemu-discuss] No start with -cpu option

[Thomas]

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
| ##### after continuing in qemu:
| s>> et_property: NULL phandle
| 
| >> =============================================================
| >> OpenBIOS 1.1 [Dec 27 2018 19:16]
| >> Configuration device id QEMU version 1 machine id 1
| >> CPUs: 1
| >> Memory: 512M
| >> UUID: 00000000-0000-0000-0000-000000000000
| >> CPU type PowerPC,G4
| milliseconds isn't unique.
| Welcome to OpenBIOS v1.1 built on Dec 27 2018 19:16
| 
| 0 >


Terminal 2:
| 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)
| (gdb) continue
| Continuing.
| ##### I waited about a minute
| ^C| Program received signal SIGINT, Interrupt.
| 0x98d2f1ff in ?? ()
| (gdb) where
| #0  0x98d2f1ff in ?? ()
| Backtrace stopped: previous frame identical to this frame (corrupt stack?)


Now, the same with '-cpu 7447a_v1.2' option.

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