Re: [Xen-devel] Commit 3a6c9 breaks QEMU on FreeBSD/Xen

[Juergen Gross <jgross@xxxxxxxx>]

On 24/01/17 17:42, Roger Pau Monné wrote:
> Hello,
> 
> The following commit:
> 
> commit 3a6c9172ac5951e6dac2b3f6cbce3cfccdec5894
> Author: Juergen Gross <jgross@xxxxxxxx>
> Date:   Tue Nov 22 07:10:58 2016 +0100
> 
> xen: create qdev for each backend device
> 
> Prevents me from running QEMU on FreeBSD/Xen, the following is printed on the
> QEMU log:
> 
> char device redirected to /dev/pts/2 (label serial0)
> xen be core: xen be core: can't open gnttab device
> can't open gnttab device
> xen be core: xen be core: can't open gnttab device
> can't open gnttab device
> 
> # xl create -c ~/domain.cfg
> Parsing config from /root/domain.cfg
> libxl: error: libxl_dm.c:2201:device_model_spawn_outcome: Domain 32:domain 32 
> device model: spawn failed (rc=-3)
> libxl: error: libxl_create.c:1506:domcreate_devmodel_started: Domain 
> 32:device model did not start: -3
> libxl: error: libxl_dm.c:2315:kill_device_model: Device Model already exited
> libxl: error: libxl.c:1572:libxl__destroy_domid: Domain 32:Non-existant domain
> libxl: error: libxl.c:1531:domain_destroy_callback: Domain 32:Unable to 
> destroy guest
> libxl: error: libxl.c:1458:domain_destroy_cb: Domain 32:Destruction of domain 
> failed
> # cat /var/log/xen/qemu-dm-domain.log
> char device redirected to /dev/pts/2 (label serial0)
> xen be core: xen be core: can't open gnttab device
> can't open gnttab device
> xen be core: xen be core: can't open gnttab device
> can't open gnttab device
> 
> I'm not really familiar with any of that code, but I think that using
> qdev_init_nofail is wrong, since on FreeBSD/Xen for example we don't yet
> support the gnttab device, so initialization of the Xen Qdisk backend can fail
> (and possibly the same applies to Linux if someone decides to compile a kernel
> without the gnttab device). Yet QEMU can be used without the Qdisk backend.

I don't think this is due to qdev_init_nofail(). As the gnttab related
messages are printed _after_ calling qdev_init_nofail() I don't see how
it could be related.

I think the error exits of xen_be_get_xendev() are just wrong in using
g_free(xendev) instead of qdev_unplug(&xendev->qdev, NULL).

I'll do a test with that modification. Could you test it in parallel?


Juergen

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel