Re: CVS commit: src/sys/kern

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

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.


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