Understanding initialization order for spice in qemu

Understanding initialization order for spice in qemu

[Christophe de Dinechin]

Hi Gerd,


When I build qemu on master with moduels enabled, and run with spice, I occasionally see:

 qemu-system-x86_64: util/module.c:136: module_load_file: Assertion `QTAILQ_EMPTY(&dso_init_list)' failed.

Interestingly, I seem to have seen that only on master, but not on my own branch. Have you ever seen the same problem? Could there be a race condition here explaining why I sometimes see it, sometimes not? Or do you think it's more likely to be a missing build dependency? Asking because I don't recall ever seeing that on a clean build.

Command line:
% qemu-system-x86_64  -display spice-app /data/VMs/deb9.qcow2



Thanks
Christophe

Re: Understanding initialization order for spice in qemu

[Alex Bennée]

Christophe de Dinechin <cdupontd@redhat.com> writes:

> Hi Gerd,
>
>
> When I build qemu on master with moduels enabled, and run with spice, I occasionally see:
>
>  qemu-system-x86_64: util/module.c:136: module_load_file: Assertion `QTAILQ_EMPTY(&dso_init_list)' failed.
>
> Interestingly, I seem to have seen that only on master, but not on my
> own branch. Have you ever seen the same problem? Could there be a race
> condition here explaining why I sometimes see it, sometimes not? Or do
> you think it's more likely to be a missing build dependency? Asking
> because I don't recall ever seeing that on a clean build.

Have you switched the config in your build directory? This is one reason
to have multiple build directories outside of the source tree.

>
> Command line:
> % qemu-system-x86_64  -display spice-app /data/VMs/deb9.qcow2
>
>
>
> Thanks
> Christophe


-- 
Alex Bennée

Re: Understanding initialization order for spice in qemu

[Gerd Hoffmann]

On Thu, Jun 18, 2020 at 01:11:44PM +0200, Christophe de Dinechin wrote:
> Hi Gerd,
> 
> 
> When I build qemu on master with moduels enabled, and run with spice, I occasionally see:
> 
>  qemu-system-x86_64: util/module.c:136: module_load_file: Assertion `QTAILQ_EMPTY(&dso_init_list)' failed.

Never saw that one.

I've noticed though the qemu build system doesn't rebuild code on cflags
changes, and switching object files from -y to -m (which adds -fPIC to
cflags) can cause build errors which go away when you rm -rf the build
tree (or at least the subdirectory where I'm hacking on) and try again.

> Asking because I don't recall ever seeing that on a clean build.

Yea, that hints it is the same problem.

HTH,
  Gerd