Re: [Qemu-devel] [PATCH] Deprecate '-enable-kvm' and '-enable-hax' in favour of '-accel'

[Thomas Huth]

On 02.05.2017 12:21, Daniel P. Berrange wrote:
> On Tue, May 02, 2017 at 12:06:40PM +0200, Thomas Huth wrote:
>> The '-enable-...' option do not make too much sense: They do not
>> allow additional parameters, using '-accel xxx' is shorter than
>> '-enable-xxx' and we're also inconsistent here, since there is
>> no '-enable-xen' option available. So let's try to convince the
>> users to use '-accel xxx' instead.
> 
> What is our general approach to deciding which of our "legacy" parameters
> are merely syntactic sugar for other parameters, vs stuff we want to
> deprecate & eventually remove ?

I'd say if the parameters can help to specify something in a short way,
then it's nice-to-have syntactic sugar. Otherwise, it's just legacy
cruft which should be removed one day.

For the accelerator options, we've got now three (!) ways to specify them:

1) -machine accel=xxx (which is the way we use it internally, thus we
should keep it)
2) -enable-xxx
3) -accel xxx

-accel xxx makes sense as syntactic sugar since it helps to keep the
command line short, but I fail to see the reason for the inconsistent
and inflexible "-enable-xxx" here, so I'd like to suggest to mark it as
deprecated so we could remove it one day (it's likely in use in the
wild, so maybe remove it in v4.0.0 in a couple of years?).

 Thomas