Re: CVS commit: src/sys/kern

[Paul Goyette <paul%whooppee.com@localhost>]

On Sun, 7 Aug 2022, Paul Goyette wrote:

> On Sun, 7 Aug 2022, Taylor R Campbell wrote:
>
> > Module Name:	src
> > Committed By:	riastradh
> > Date:		Sun Aug  7 21:17:18 UTC 2022
> >
> > Modified Files:
> > 	src/sys/kern: kern_module.c
> >
> > Log Message:
> > module(9): Disable module autounload by default.
> >
> > I don't know why this was ever enabled by default; many modules are
> > still not safe to unload, let alone autounload.  If any autounload is
> > to happen by default, it should only be for modules that have opted
> > into it in some way after audit.
>
> One reason for the current behavior involves the modules used for
> various emulations.  When a file is executed, and none of the
> currently-loaded modules can "deal" with it, we load _all_ of the
> available emulation modules with the hope that one of them will
> "deal with" the new executable, and with the expectation that the
> remaining emulation modules will just "go away".
>
> Modules that are known to be unsafe to unload should declare that
> in their modcmd() unload (by returning EBUSY).  After all, one
> might well expect that the module itself is the most likely place
> that the unloadable status would be known.
>
> Making no-autounload as the default seems like using a 20-pound
> sledge hammer on a carpet tack.

I might also note that making such a fundamental behavior change
when we're so close to the -10 release, without actually providing
the suggested "opt-in" mechanism to retain current behavior, is
not very user friendly.   :-)

At least this should be discussed (on tech-kern@, perhaps) before
being unilaterally decided and committed.  IIRC, we had this
discussion some time ago, and the decision at that time was to
retain current behavior.  Unfortunately, I didn't save any pointer
to that old discussion.  :-(

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+--------------------+--------------------------+----------------------+
| Paul Goyette       | PGP Key fingerprint:     | E-mail addresses:    |
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