Re: [PATCH 00/18] x86: new .insn directive

[Jan Beulich <jbeulich@suse.com>]

On 07.03.2023 21:33, H.J. Lu wrote:
> On Mon, Mar 6, 2023 at 1:26 AM Jan Beulich <jbeulich@suse.com> wrote:
>>
>> On 03.03.2023 17:50, H.J. Lu wrote:
>>> X86 encoding scheme is quite complex.  It may get even more complex in
>>> the future.
>>
>> Indeed. Also some complexities did exist only transiently, like AMD's
>> DREX. MVEX is mentioned in the series, and I'm not sure whether to
>> call this "historic" as well. However, ...
>>
>>>  I suggest we wait for a while so that we can get clear pictures
>>> what the future encoding scheme looks like.
>>
>> ... I have to admit that I'm puzzled by this suggestion. The rate at
>> which new encoding schemes appear is pretty low. So unless you know
>> of something to see the (public) light of day soon, I wonder what
>> meaning you assign to "a while". The plan certainly is for this work
>> to land well in time for 2.40, unless there are clear technical
>> issues speaking against it. In no event do I plan to wait very long
>> with committing not directly .insn-related changes in the series,
>> like patches 06 ... 09 or even 10, and maybe 04 as well as 12.
>>
>> I shall perhaps also add that I view entirely new encoding schemes
>> as less of a problem - support for them can be added to .insn
>> handling incrementally. What could be more problematic are changes
>> to one of the existing schemes.
> 
> We will evaluate if these changes will cause any potential issues for
> the future.

Okay, but please supply me with a time frame for this activity. It's
not reasonable to have me sit on this kind of work (and potentially
have to rebase it repeatedly over other work) for an extended period
of time. Furthermore, should potential issues be found, there'll
need to be enough detail for me to actually address these (rather
than wait until such features would become publicly known).

In the absence of a timeline I'll get v2 out soonish (I've found
that I failed to remember to re-run the testsuite on a broader set
of sub-targets after adding the immediate operands handling and the
conversion of some of the existing testcases; hence some adjustments
were needed there), and then wait like two weeks for comments of any
kind. Should none surface, I think I can rightfully commit the whole
lot then. (As indicated, I may commit a subset ahead of submitting
v2, not the least to limit the volume of the re-submission. But of
course again only unless comments surface which would need
addressing.)

Jan