Re: [Qemu-discuss] qemu hangs

[Peter Maydell]

On 16 August 2016 at 17:50, Nerijus Baliūnas
<address@hidden> wrote:
> I tried to debug with gdb:
>
> # gdb /usr/bin/qemu-system-alpha
> Reading symbols from /usr/bin/qemu-system-alpha...Reading symbols from
> /usr/lib/debug/usr/bin/qemu-system-alpha.debug...done.
> done.
> (gdb) r -S -no-user-config -nodefaults -nographic -M none -qmp
> unix:/var/lib/libvirt/qemu/capabilities.monitor.sock,server,nowait -pidfile
> /var/lib/libvirt/qemu/capabilities.pidfile -daemonize
> Starting program: /usr/bin/qemu-system-alpha -S -no-user-config -nodefaults
> -nographic -M none -qmp
> unix:/var/lib/libvirt/qemu/capabilities.monitor.sock,server,nowait -pidfile
> /var/lib/libvirt/qemu/capabilities.pidfile -daemonize
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib64/libthread_db.so.1".
> [New Thread 0x7fffc9708700 (LWP 12596)]
> Detaching after fork from child process 12597.
> ^C
> Thread 1 "qemu-system-alp" received signal SIGINT, Interrupt.
> 0x00007fffdabc2dad in read () at ../sysdeps/unix/syscall-template.S:84
> 84      T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
>
> (gdb) bt
> #0  0x00007fffdabc2dad in read () at ../sysdeps/unix/syscall-template.S:84
> #1  0x00005555557d63d3 in os_daemonize (__nbytes=1, __buf=0x7fffffffdfdf,
> __fd=<optimized out>)
>     at /usr/include/bits/unistd.h:44
> #2  0x00005555557d63d3 in os_daemonize () at
> /usr/src/debug/qemu-2.7.0-rc2/os-posix.c:224
> #3  0x000055555573ac9e in main (argc=<optimized out>, argv=<optimized out>,
> envp=<optimized out>)
>     at /usr/src/debug/qemu-2.7.0-rc2/vl.c:3989

This is the outer process waiting for the child process to tell
it it's got started in os_daemonize().

Does QEMU still hang if you don't pass it -daemonize ? If so,
then it will be easier to debug that. If the hang is actually
caused by the daemonize code then you'll need to get gdb to
debug into the child process of the fork().

thanks
-- PMM