On Fri, Jan 05, 2024 at 07:04:02AM +0000, 陈 晟祺 wrote:
Hi,
> > zfs-dkms is the failsafe in case the zfs-modules-<kernelversion> package is
> > *not* installed
> > (for example, because this is the first slow box I'm installing this kernel
> > or this version of
> > zfs-dkms on and I don't yet have a corresponding zfs-modules package).
>
> Let's imagine you install modules pkg first, then dkms pkg, which skips
> building because you have
> "same" modules installed. After some days you accidentally uninstalled the
> modules pkg, then how
> would the dkms pkg know and start the building? There is no such mechanism
> according to my knowledge.
I'd like to start by saying that installing a zfs-modules-<kernelversion>
package is something only few people would probably do, people who have good
reasons for going off the beaten path.
I submit that it's not unreasonable to expect such people to be extra careful
and be aware of the risks inherent in what they are doing.
That said, I suppose a dpkg trigger could be used; or the postrm script of the
zfs-modules-<kernelversion> package could trigger the module build if zfs-dkms
is installed. But frankly, I'm a great believer in allowing people to shoot
themselves in the foot if they so desire. Expert features (which this would be)
don't call for nanny automation.
> Even though such mechanism can be implemented by dkms, let's dig deeper into
> details: how would dkms
> know that your prebuilt version and dkms source files are "the exact same"
> and decide to skip? Designing
> such a mechanism would be either cumbersome for developers, or confusing for
> users, I suppose.
I don't think it needs to do that. If the zfs-modules-<kernelversion> package
is installed, that means the admin is taking care of things.
If they have outdated kernel modules installed, it's their problem and not up
to dkms or zfs-dkms maintainers to fix for them. You don't have to do
everything for everyone.
I'd say it would be sufficient to document that installing a
zfs-modules-<kernelversion> package is not officially supported, and has the
following consequences:
1. zfs-dkms won't build a new module for <kernelversion>;
2. if you subsequently remove zfs-modules-<kernelversion>, you'll be left
without a zfs module for <kernelversion> unless you trigger a zfs-dkms build
yourself.
FWIW, you could also look at it from a green angle: building the modules when
it's not necessary consumes extra electricity and is thus wasteful.
Best regards,
András
--
I break into song if I can't find the key.
