Re: [PATCH] CHANGELOG.md: Make PV shim smaller by factoring out HVM-specific shadow code

[Jan Beulich <jbeulich@xxxxxxxx>]

On 31.03.2021 16:00, George Dunlap wrote:
> 
> 
>> On Mar 31, 2021, at 2:54 PM, Jan Beulich <jbeulich@xxxxxxxx> wrote:
>>
>> On 31.03.2021 15:52, Ian Jackson wrote:
>>> George Dunlap writes ("Re: [PATCH] CHANGELOG.md: Make PV shim smaller by 
>>> factoring out HVM-specific shadow code"):
>>>> I don’t understand why the two of you are downplaying your work so much. 
>>>> Yes, these are all only incremental improvements; but they are 
>>>> improvements; and the cumulative effect of loads of incremental 
>>>> improvements can be significant.  Communicating to people just what the 
>>>> nature of all these incremental improvements are is important.
>>>
>>> I agree with George here.
>>>
>>> There ae a number of reasons why behind-the-scenes work with little
>>> (intentional) user-visible impact are useful to note in the
>>> CHANGELOG.md.  With my Release Manager hat on I would like to see, for
>>> example,
>>>
>>>>> + - Factored out HVM-specific shadow code, allowing PV shim to be slimmer
>>>
>>> something about htis work in the CHANGELOG.md.
>>>
>>> IDK precisely, and I don't think George does either, what a good and
>>> accurate statement is.  But I guess we will go with the text above if
>>> we don't get something better.
>>
>> At the very least the part after the comma ought to be deleted. As
>> said in an earlier reply, at least the shim default config disables
>> shadow code anyway, so the factoring out has no effect there.
> 
> Thanks.  So when you wrote the series, what was your motivation?  Did you 
> have a particular technical outcome in mind?  Or did it just bother you that 
> there was HVM-only code in a PV-only build? :-)

What bothers me are more the implications - it being rather hard in
many cases, and in particular in shadow code, to be able to tell what
paths are involved in the handling of what kind(s) of guests. This
has made more time consuming investigation of (suspected) misbehavior
in more than one case.

Jan