Re: [Qemu-devel] [PATCH 01/17] qidl: add QEMU IDL processor

[Avi Kivity]

On 06/05/2012 03:19 PM, Gerd Hoffmann wrote:
>   Hi,
> 
>> <snip>
>> 
>> Suggestion: add a _guest marker for ordinary state.  Fail the build on
>> unmarked fields.  This ensures that some thought is given to each field,
>> instead of having a default that may be correct most of the time, but
>> not always.
>> 
>> Suggestion: add a mandatory position hint (_guest(7) or _pos(7)) that
>> generates ordering within the fields.  This decouples the order of lines
>> in the struct from the protocol, so you can add state where it make
>> sense, or rearrange lines when they don't, and detect copy/paste errors.
> 
> I wouldn't make the position mandatory.  I expect the next generation
> migration wire protocol transmits the field names anyway, so the
> ordering will not matter any more, we need it for compatibility with
> today's format only.

We can remove the position hints when the old protocol is no longer
supported, but until then, it's IMO too easy to break compatibility by
moving lines around.


-- 
error compiling committee.c: too many arguments to function