Re: [Qemu-devel] [PATCH v2] qemu-m68k: add support for interrupt masking/unmasking

[Waldemar Brodkorb]

Hi Stefan,
Stefan Weil wrote,

> Am 03.04.2015 um 10:04 schrieb Waldemar Brodkorb:
> >Hi Stefan,
> >Stefan Weil wrote,
> >
> >>Am 29.03.2015 um 17:53 schrieb Stefan Weil:
> >>>Am 29.03.2015 um 15:47 schrieb Waldemar Brodkorb:
> >>>>Hi Stefan,
> >>>>Stefan Weil wrote,
> >>>>
> >>>>>You can debug the kernel panic by attaching a cross debugger to the
> >>>>>running kernel.
> >>>>>If you have a kernel image with debug symbols, this is very
> >>>>>comfortable.
> >>>>How would I do this?
> >>>>Tried to start qemu with -s -S and then attach with my cross-gdb
> >>>>using the kernel with debug symbols. But gdb does not recognize the
> >>>>panic:
> >>>>Command: mdev -s
> >>>>Command: ifconfig lo 127.0.0.1 up
> >>>>Execution Finished, Exiting
> >>>>
> >>>>Sash command shell (version 1.1.1)
> >>>>/> Kernel panic - not syncing: Attempted to kill init!
> >>>>exitcode=0x0000000b
> >>>>
> >>>>---[ end Kernel panic - not syncing: Attempted to kill init!
> >>>>exitcode=0x0000000b
> >>Is this the kernel panic which you get? I did not have a closer look
> >>on it before, but now I see that it is something quite common:
> >>
> >>Your kernel runs an init script (or binary) which terminates
> >>(obviously normally). Then the kernel does not know what to
> >>do, so it throws a kernel panic "Attempted to kill init".
> >>
> >>Usually the init process should only terminate at a system shutdown.
> >The init is a simple C programm called simpleinit.
> >The strange thing is, why it only happens with the ull version
> >of qemu and not with the other one?
> >http://www.openadk.org/cgi-bin/gitweb.cgi?p=openadk.git;a=blob;f=package/simpleinit/src/simpleinit.c;h=291f88f479cf9ad4e24d727bc09120d0e6739ac3;hb=HEAD
> >
> >best regards
> >         Waldemar
> 
> Do you see any console output from that init process?
> Can you build it with the DEBUGGING macro included?
> 
> There is one program exit without a log message in
> function read_inittab:
> 
>         if (numcmd == 0)
>                  _exit(1);
> 
> Add a printf or an err call there, too. Add also some log
> messages in main. main includes an endless for loop,
> so that init program is supposed to run without
> termination. By additional log messages, it should
> be possible to see why it terminates nevertheless.
> 
> As soon as the point of termination is known, we can
> think of the relation to the ULL postfix.

Shell invoked to run file: /etc/rc

Sash command shell signal handler
Command: echo Starting OpenADK
Starting OpenADK
Command: hostname openadk
Command: mount -t proc proc /proc
Command: mount -t sysfs sys /sys
Command: mkdir -m 755 /dev/pts
Command: mount -t devpts devpts /dev/pts
Command: mount -t tmpfs -o size=8M tmpfs /tmp
Command: chmod 1777 /tmp
Command: mkdir -p /var/log
Command: mkdir -p /var/run
Command: mkdir -p /var/tmp
Command: mdev -s
Command: ifconfig lo 127.0.0.1 up
Execution Finished, Exiting

Sash command shell exit with 0
toks= -/bin/sh (null)  
tty= console
termcap= linux
init: main loop
Sash command shell (version 1.1.1)

Sash command shell signal handler
/> Kernel panic - not syncing: Attempted to kill init!
exitcode=0x0000000b

---[ end Kernel panic - not syncing: Attempted to kill init!
exitcode=0x0000000b

The code execution path is, kernel exec simpleinit and simpleinit
exec sash. After the second call to sash, when /etc/rc is finished,
2-3 seconds later the kernel panic's.

I had a similar issue once I have used busybox hush instead of sash.
The switching to sash fixed the issue for me and now when adding ull
it happens again.

Sash code ( i added some printf locally )
http://www.openadk.org/cgi-bin/gitweb.cgi?p=openadk.git;a=tree;f=package/sash/src;h=476c254af2fb4c211d32d9418807736970fbb536;hb=HEAD

Discussion about the issue with hush:
http://lists.busybox.net/pipermail/busybox/2014-September/081634.html

best regards
 Waldemar