The comment for that option states that the default value is 'none' but
it was not set by the code.

Fixes: 700450449377be4bf923e91d00f8fe8cf0975f66
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
---
 src/qemu/qemu_conf.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index 77fd7f6df7..68b086be54 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -295,6 +295,8 @@ virQEMUDriverConfigPtr virQEMUDriverConfigNew(bool privileged,
                              &cfg->nfirmwares) < 0)
         return NULL;
 
+    cfg->deprecationBehavior = g_strdup("none");
+
     return g_steal_pointer(&cfg);
 }
 
-- 
2.30.2

On 4/13/21 11:10 AM, Pavel Hrdina wrote:
> The comment for that option states that the default value is 'none' but
> it was not set by the code.
> 
> Fixes: 700450449377be4bf923e91d00f8fe8cf0975f66
> Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
> ---
>   src/qemu/qemu_conf.c | 2 ++
>   1 file changed, 2 insertions(+)
> 

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

Michal

On Tue, Apr 13, 2021 at 11:10:18 +0200, Pavel Hrdina wrote:
> The comment for that option states that the default value is 'none' but
> it was not set by the code.
> 
> Fixes: 700450449377be4bf923e91d00f8fe8cf0975f66
> Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
> ---

Could you please elaborate what the problem of not setting it is?

'none' the same as NULL should result in doing nothing.

On 4/13/21 12:53 PM, Peter Krempa wrote:
> On Tue, Apr 13, 2021 at 11:10:18 +0200, Pavel Hrdina wrote:
>> The comment for that option states that the default value is 'none' but
>> it was not set by the code.
>>
>> Fixes: 700450449377be4bf923e91d00f8fe8cf0975f66
>> Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
>> ---
> 
> Could you please elaborate what the problem of not setting it is?
> 
> 'none' the same as NULL should result in doing nothing.
> 

Is it? In qemuBuildCompatDeprecatedCommandLine() a string is initialized 
to cfg->deprecationBehavior and then passed to TypeFromString() which 
fails and thus VIR_WARN() is printed. I believe that's where crash can 
occur.

Michal

On Tue, Apr 13, 2021 at 13:03:44 +0200, Michal Privoznik wrote:
> On 4/13/21 12:53 PM, Peter Krempa wrote:
> > On Tue, Apr 13, 2021 at 11:10:18 +0200, Pavel Hrdina wrote:
> > > The comment for that option states that the default value is 'none' but
> > > it was not set by the code.
> > > 
> > > Fixes: 700450449377be4bf923e91d00f8fe8cf0975f66
> > > Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
> > > ---
> > 
> > Could you please elaborate what the problem of not setting it is?
> > 
> > 'none' the same as NULL should result in doing nothing.
> > 
> 
> Is it? In qemuBuildCompatDeprecatedCommandLine() a string is initialized to
> cfg->deprecationBehavior and then passed to TypeFromString() which fails and
> thus VIR_WARN() is printed. I believe that's where crash can occur.

Ah, right. That's the stuff that should be in the commit message then.

On Tue, Apr 13, 2021 at 12:53:23PM +0200, Peter Krempa wrote:
> On Tue, Apr 13, 2021 at 11:10:18 +0200, Pavel Hrdina wrote:
> > The comment for that option states that the default value is 'none' but
> > it was not set by the code.
> > 
> > Fixes: 700450449377be4bf923e91d00f8fe8cf0975f66
> > Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
> > ---
> 
> Could you please elaborate what the problem of not setting it is?
> 
> 'none' the same as NULL should result in doing nothing.

When the config is not set in qemu.conf libvirt will print the following
warning if there is any deprecated command used:

warning : qemuBuildCompatDeprecatedCommandLine:10393 : Unsupported deprecation behavior '(null)' for VM 'test'

So no NULL and 'none' are not the same.

We could fix qemuBuildCompatDeprecatedCommandLine() but I figured that
this is what we do with other options so that would be preferred
solution.

Pavel

On Tue, Apr 13, 2021 at 13:09:15 +0200, Pavel Hrdina wrote:
> On Tue, Apr 13, 2021 at 12:53:23PM +0200, Peter Krempa wrote:
> > On Tue, Apr 13, 2021 at 11:10:18 +0200, Pavel Hrdina wrote:
> > > The comment for that option states that the default value is 'none' but
> > > it was not set by the code.
> > > 
> > > Fixes: 700450449377be4bf923e91d00f8fe8cf0975f66
> > > Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
> > > ---
> > 
> > Could you please elaborate what the problem of not setting it is?
> > 
> > 'none' the same as NULL should result in doing nothing.
> 
> When the config is not set in qemu.conf libvirt will print the following
> warning if there is any deprecated command used:
> 
> warning : qemuBuildCompatDeprecatedCommandLine:10393 : Unsupported deprecation behavior '(null)' for VM 'test'
> 
> So no NULL and 'none' are not the same.
> 
> We could fix qemuBuildCompatDeprecatedCommandLine() but I figured that
> this is what we do with other options so that would be preferred
> solution.

Sure. I agree, but as I've noted in reply to Michal, such explanation
should be part of the commit message.