Re: [Qemu-devel] [PATCH v4 2/2] vl: Deprecate auto-loading of qemu.conf

[Eduardo Habkost <ehabkost@redhat.com>]

On Wed, Oct 04, 2017 at 09:23:08AM -0300, Eduardo Habkost wrote:
> On Wed, Oct 04, 2017 at 07:42:17AM +0200, Markus Armbruster wrote:
> > Eduardo Habkost <ehabkost@redhat.com> writes:
> > 
> > > In case there were options set in the default config file, print
> > > a warning so users can update their scripts.
> > >
> > > If somebody wants to keep the config file as-is, avoid the
> > > warning and use a command-line that will work in future QEMU
> > > versions, they can use:
> > >
> > >  $QEMU -no-user-config -readconfig /etc/qemu/qemu.conf
> > >
> > > I was going to include the suggestion in the warning message, but
> > > I thought it could make it more confusing.  The suggestion is
> > > documented in qemu-doc.texi.
> > >
> > > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> > > ---
> > > Changes v3 -> v4:
> > > * Use warn_report() instead of error_report("warning: ...")
> > >   (Eric Blake)
> > > * Document as a deprecated feature in qemu-doc.texi
> > > * Update subject line
> > >   (was: "vl: Print warning when a default config file is loaded")
> > >
> > > Changes v2 -> v3:
> > > * Rebase (no code changes)
> > > * Commit message update: suggest -no-user-config
> > > ---
> > >  vl.c          | 6 ++++++
> > >  qemu-doc.texi | 8 ++++++++
> > >  2 files changed, 14 insertions(+)
> > >
> > > diff --git a/vl.c b/vl.c
> > > index 3fed457921..1b0ecdf74e 100644
> > > --- a/vl.c
> > > +++ b/vl.c
> > > @@ -3066,6 +3066,12 @@ static int qemu_read_default_config_file(void)
> > >          return ret;
> > >      }
> > >  
> > > +    if (ret > 0) {
> > > +        loc_set_none();
> > 
> > Sure we need this here?
> 
> IIRC we needed it in the original version, but I don't remember
> why.  I will check this.

This is the result if we don't clear error location state:

  $ ./x86_64-softmmu/qemu-system-x86_64 -monitor stdio -display none -device foobar
  qemu-system-x86_64: -device foobar: warning: Future QEMU versions won't load /usr/local/etc/qemu/qemu.conf automatically
                      ^^^^^^^^^^^^^^

However, it's probably better to do this right after the loop,
just like we already do in the second option parsing loop:

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
diff --git a/vl.c b/vl.c
index f9acc17c01..a8fd247d71 100644
--- a/vl.c
+++ b/vl.c
@@ -3067,7 +3067,6 @@ static int qemu_read_default_config_file(void)
     }
 
     if (ret > 0) {
-        loc_set_none();
         warn_report("Future QEMU versions won't load %s automatically",
                      CONFIG_QEMU_CONFDIR "/qemu.conf");
     }
@@ -3224,6 +3223,11 @@ int main(int argc, char **argv, char **envp)
             }
         }
     }
+    /*
+     * Clear error location left behind by the loop.
+     * Best done right after the loop.  Do not insert code here!
+     */
+    loc_set_none();
 
     if (userconfig) {
         if (qemu_read_default_config_file() < 0) {

-- 
Eduardo