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Re: usrmerge -- plan B?




Firstly, thanks for your measured and helpful contributions to this
very unfortunate thread.

Simon McVittie writes ("Re: usrmerge -- plan B?"):
> I hope we can agree that unnecessary complexity is technical debt, but
> necessary complexity is necessary: if complexity exists for a reason,
> then the "cost" of the complexity should be compared with the benefit
> of having it, to decide whether the complexity needs to be kept.

I definitely agree with this.

> In the case of unmerged /usr, the only benefits I'm aware of for the more
> complex case (unmerged /usr) are circular: existing Debian installations
> have it, so switching to merged /usr is a change;

I think this is true for Debian itself now that we have bitten the
bullet of requiring /usr to be mounted along with /, early during
boot.  (For the record I think that was a good decision.)

Unmerged /usr could have continuing benefits for Debian derivatives
who have avoided requiring early mounting of /usr.  IDK whether such
derivatives exist.  They could do, if they support a narrower range of
approaches to storage access than Debian proper.  If such derivatives
exist then Debian adopting merged /usr would be likely to cause
problems for them, as we would introduce changes in Debian which would
be bugs in those derivatives.  I don't know how serious a problem that
would be.

I think it would be good to hear from any derivatives in this
position.  We should probably ask them more formally than by having a
horrible flamewar on -devel: ie, in a way that invites the expression
of concerns and which reassures people that they will not be flamed or
dismissed.  That would satisfy what I see as our social duty to
consult our downstreams.  And if we did that and didn't get replies,
that might give us confidence that such derivatives don't exist.  So
we could go ahead with a clear conscience.

Also, there is a social cost of pressing for change.  That could have
been minimised by taking a slow, measured, and consensual approach.
Other substantial changes in Debian have been achieved successfully
with few people getting upset.

Unfortunately the opportunity to do that for mandatory merged-/usr has
been lost.  Now, that transition would necessarily generate
significant ill-will.  Personally I doubt it is worth it.

> Now, it's entirely valid to trade off long-term complexity (unmerged
> /usr) against short-term complexity (applying the /usr merge); one
> possible answer to whether we should eliminate some unnecessary long-term
> complexity is "yes, but not yet" (and the reason for this entire thread is
> that part of the transition happened in the wrong order, with buildd and
> pbuilder chroots becoming merged-/usr sooner than they should have done).

Another possible answer is "yes but we should achieve this in a
different way".  That seems to be Adam's proposal.

Certainly I hope you agree with me that a transition of this magnitude
ought to be properly planned; the plan should be consulted on, with
real attention paid to feedback.

> If I was wrong in assuming good faith and you were being argumentative for
> the sake of being argumentative, please stop: that is not constructive.
> 
> Either way, please don't call me stupid. That is not *at all*
> constructive - especially if you want things you say in future to change
> my opinion on anything! - and contributes to an atmosphere of hostility
> that drives away Debian contributors.

I absolutely agree with this.  Some of the messages from merged-/usr
sceptics have been very bad (and I have said so in private and public
messages).

But also, right now I'm afraid that the most vigorous proponent of
merged-/usr, here on this list, is being extremely dismissive of
feedback.  The approach Marco is taking is generating ill-will amongst
existing contributors (some of whom will then inevitably lash out, bad
as that is), and it is attracting the attention of undesirables.

If you cannot persuade Marco to let you lead the discussion, I think
you should distance yourself from him.

Unfortunately that means that while a properly planned and executed
transition to mandatory merged-/usr might well have offered overall
technical benefits for the Debian ecosystem, this is not now socially
possible and pressing on is not worth the social costs of being seen
to bulldoze opposition.

Ian.

-- 
Ian Jackson <ijackson@xxxxxxxxxxxxxxxxxxxxxx>   These opinions are my own.

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