Re: [Qemu-devel] [PATCH 4/4] qapi: Rename ChardevBackend member "memory" to "ringbuf"

[Markus Armbruster <armbru@redhat.com>]

Amos Kong <akong@redhat.com> writes:

> On Fri, Jun 28, 2013 at 07:19:39PM +0200, Markus Armbruster wrote:
>> Eric Blake <eblake@redhat.com> writes:
>> 
>> > On 06/27/2013 08:22 AM, Markus Armbruster wrote:
>> >> Commit 1da48c6 called the new member "memory" after commit 3949e59
>> >> standardized "ringbuf".  Rename for consistency.
>> >> 
>> >> However, member name "memory" is visible in QMP since 1.5.  It's
>> >> undocumented just like the driver name.  Keep it working anyway.
>> >> 
>> >> Cc: qemu-stable@nongnu.org
>> >> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>> >> ---
>> >>  qapi-schema.json |  6 ++++--
>> >>  qemu-char.c      | 11 ++++++-----
>> >>  2 files changed, 10 insertions(+), 7 deletions(-)
>> >> 
>> >> diff --git a/qapi-schema.json b/qapi-schema.json
>> >> index 6445da6..b3df8a5 100644
>> >> --- a/qapi-schema.json
>> >> +++ b/qapi-schema.json
>> >> @@ -3277,9 +3277,9 @@
>> >>  ##
>> >>  # @ChardevRingbuf:
>> >>  #
>> >> -# Configuration info for memory chardevs
>> >> +# Configuration info for ring buffer chardevs.
>> >>  #
>> >> -# @size: #optional Ringbuffer size, must be power of two, default is 65536
>> >> +# @size: #optional ring buffer size, must be power of two, default is 65536
>> >>  #
>> >>  # Since: 1.5
>> >>  ##
>> >> @@ -3310,6 +3310,8 @@
>> >>                                         'spicevmc' : 'ChardevSpiceChannel',
>> >>                                         'spiceport' : 'ChardevSpicePort',
>> >>                                         'vc'     : 'ChardevVC',
>> >> +                                       'ringbuf': 'ChardevRingbuf',
>> >> +                                       # next one is just for compatibility
>> >>                                         'memory' : 'ChardevRingbuf' } }
>> >
>> > Does JSON allow comments in the middle of content?  Is this going to
>> > screw up Amos' work on introspection?  You may need to instead have a
>> > comment before the open '{' stating that 'memory' is an alias within the
>> > union for back-compat reasons.
>
> I didn't parse the json file by myself. I just used the parsed
> dictionary. So it only needs to make qapi.py happy.
>
>> RFC 4627 doesn't do comments at all.
>> 
>> This file is parsed by scripts/qapi.py, which as far as I can tell
>> ignores lines starting with '#' anywhere in the input.
>
> Not anywhere, only start with '#'

Isn't that what I said?

> | def parse_schema(fp):
> |     exprs = []
> |     raw_exprs = []
> |     expr = ''
> |     expr_eval = None
> | 
> |     for line in fp:
> |         if line.startswith('#') or line == '\n':
>
>       # ignores lines starting with '#' anywhere
>           if line.strip().startswith('#')   
>
> |             continue
> | 
>
>
> So we should not add this kind of comment for back-compat.

Now I'm confused.  My patch adds a line that starts with '#'.
parse_schema() ignores it.  Works as designed.  Why do you think we
shouldn't do that?