Re: [PATCH] modprobe: install default configuration

[Lubomir Rintel <lkundrak@v3.sk>]

On Wed, 2016-04-13 at 01:11 -0300, Lucas De Marchi wrote:
> On Tue, Mar 29, 2016 at 7:27 AM, Lubomir Rintel <lkundrak@v3.sk>
> wrote:
> >=20
> > On Fri, 2016-03-04 at 02:02 -0300, Lucas De Marchi wrote:
> > >=20
> > > On Wed, Mar 2, 2016 at 1:28 PM, Lubomir Rintel <lkundrak@v3.sk>
> > > wrote:
> > > >=20
> > > >=20
> > > > On Wed, 2016-03-02 at 16:07 +0000, De Marchi, Lucas wrote:
> > > > >=20
> > > > >=20
> > > > > On Wed, 2016-03-02 at 16:55 +0100, Marco d'Itri wrote:
> > > > > >=20
> > > > > >=20
> > > > > >=20
> > > > > > On Mar 02, Lubomir Rintel <lkundrak@v3.sk> wrote:
> > > > > >=20
> > > > > > >=20
> > > > > > >=20
> > > > > > >=20
> > > > > > >=20
> > > > > > > The kernel maintainers seem opposed to fixing this in
> > > > > > > kernel
> > > > > > > (despite a similar
> > > > > > > thing has been done with loop block devices) [1]. Let's
> > > > > > > fix
> > > > > > > this
> > > > > > > my
> > > > > > > overriding the
> > > > > > > defaults from userspace.
> > > > > > Because, guess what? This breaks userspace.
> > > > > > Feel free to configure your system this way if it is what
> > > > > > you
> > > > > > want.
> > > > > More context: https://github.com/systemd/systemd/pull/2778
> > > > >=20
> > > > > Marco, could you be more specific on how this breaks
> > > > > userspace?
> > > > > It
> > > > > seems already pretty much broken to me. We can even argue if
> > > > > people
> > > > > wants the broken system back they can equally well configure
> > > > > their
> > > > > system to do that (even putting on /etc to override what was
> > > > > set
> > > > > on
> > > > > /usr/lib).
> > > > >=20
> > > > > The commit message doesn't reflect the feedback from kernel
> > > > > maintainers
> > > > > very well IMO.=C2=A0=C2=A0Main argument there was the compile-t=
ime
> > > > > option
> > > > > rather
> > > > > than allowing it to be in runtime like this one.
> > > > I thought that this part of feedback was a bit uninformed or
> > > > there
> > > > has
> > > > been some misunderstanding (perhaps on my side). There already
> > > > are
> > > > options; the kernel patch just changed defaults for the options
> > > > --
> > > > not
> > > > hardcoding the values or anything like that; just allowing to
> > > > choose
> > > > different defaults at compile time.
> > > >=20
> > > > The point was that if the user merely does "make oldconfig" to
> > > > update
> > > > his kernel configuration the behavior wouldn't change. Thus it
> > > > would be
> > > > safe for anyone to install an new kernel on an old distro even
> > > > if
> > > > they're relying on the ancient behavior.
> > > >=20
> > > > On the other hand, it would still allow for behavior change on
> > > > distro
> > > > upgrades. I'm assuming it's okay to do that -- far bigger
> > > > changes
> > > > regularly occur and users of exotic interfaces often end up
> > > > adjusting
> > > > their tooling on major upgrades.
> > > I would say the better patch to the kernel would be to bite the
> > > bullet
> > > and change the default.
> > > The default is bad as shown by your example and people
> > > complaining
> > > about the behavior. With a patch to kmod we are acknowledging the
> > > default is bad and changing it, just like we would be if the
> > > patch to
> > > the kernel was applied (i.e. people wanting the old behavior back
> > > would have to change the option in kernel cmdline or
> > > /etc/modprobe.d)
> > >=20
> > > Anyway, I don't oppose to applying it here, but I'll wait some
> > > more
> > > days for people to chime in.
> > Hi, I'm wondering if this could be moved forwards or needs some
> > more
> > discussion/work?
> Maybe getting an ack from kernel people involved since we still got
> no
> feedback. Unfortunately our archives vanished and would be hard to
> point them to the whole thread. Do you want to CC them here?

Sorry for the late reply; I'm not sure whom to include; you probably
have a better idea. Please feel free to CC whoever might be interested
in providing feedback to this.

> Lucas De Marchi

Lubo