Re: [Qemu-devel] [PATCH v7 2/9] qemu-binfmt-conf.sh: make opts -p and -c boolean

[Eric Blake]

On 3/12/19 4:39 PM, Unai Martinez Corral wrote:
> 2019/3/12, Eric Blake:
>>
>> On 3/12/19 2:51 PM, Unai Martinez-Corral wrote:
>>> This patch breaks backward compatibility.
>>>
>>
>> Is it worth a mention why we don't consider backwards-compatibility for
>> this script to be very important?
> 
> 'persistent' is a quite recent feature (8 monts) which seems not to be
> widely know. See, e.g., the references in
> https://github.com/umarcor/qus#similar-projects-blog-posts-and-other-references.

This rationale belongs in the commit message.

> So I think that it is almost harmless.

I don't know the prospective audience of qemu-binfmt-conf.sh to know if
it is harmless or not. I'm just trying to make sure that if your commit
DOES end up breaking something, that whoever ends up bisecting back to
your commit message has enough information to know whether they need to
fix their workflow or propose a patch to revert your change.  I also
don't know if this is the sort of change that should go through the
formal qemu-deprecation.texi policy of two cycles of warnings about
pending change in behavior before we actually flip the switch, or if it
is indeed a small enough audience that a formal deprecation is too much
effort.

Backward-incompatible changes are not necessarily wrong, but they
DESERVE some specific attention in the commit message so that people
reading the commit can have warm fuzzies about the change.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

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