Re: [Qemu-devel] Crash when deleting the diag288 watchdog

[Thomas Huth <thuth@redhat.com>]

On 16.08.2017 11:23, Cornelia Huck wrote:
> On Wed, 16 Aug 2017 07:05:37 +0200
> Thomas Huth <thuth@redhat.com> wrote:
> 
>>  Hi,
>>
>> I recently noticed that QEMU abort()s if you try to remove the diag288
>> watchdog. For example:
>>
>> $ qemu-system-s390x -nographic -nodefaults -S -monitor stdio
>> QEMU 2.9.92 monitor - type 'help' for more information
>> (qemu) device_add diag288,id=x
>> (qemu) device_del x
>> **
>> ERROR:/home/thuth/devel/qemu/qdev-monitor.c:872:qdev_unplug: assertion
>> failed: (hotplug_ctrl)
>> Aborted (core dumped)
>>
>> This is ugly, can we fix this somehow? For example, should the diag288
>> device be hot-pluggable at all, or can it only be used via the
>> "-watchdog" parameter instead? In the latter case, we could simply mark
>> the device with "user_creatable = false", I guess?
> 
> I don't think the diag288 watchdog should be hotpluggable. IIUC, it is
> simply present on z/VM (and I don't think it's different on LPAR, but I
> could not find docs for that). So yes, user_creatable = false sounds
> like the right thing to do.

I tried that now, but it does not work - when I specify the -watchdog
parameter, I get a "Parameter 'driver' expects pluggable device type"
with that modification.
I think the best option is to use "hotpluggable = false" instead...

> Related: We currently only handle diag288 via kvm if I did not miss
> something. It probably makes sense to wire it up for tcg as well.

Sounds like a good idea, yes... are you going to send a patch, or shall
I put it on my todo list?

 Thomas