Re: [GIT PULL] kdbus for 4.1-rc1

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Apr 15, 2015 at 10:18:46AM +0200, Martin Steigerwald wrote:
> Am Dienstag, 14. April 2015, 18:36:28 schrieb Andy Lutomirski:
> > On Mon, Apr 13, 2015 at 1:22 PM, Al Viro <viro@zeniv.linux.org.uk> 
> wrote:
> > > On Mon, Apr 13, 2015 at 09:42:17PM +0200, Greg Kroah-Hartman wrote:
> > >> > I remain opposed to this half thought out trash of an ABI for the
> > >> > meta-data.
> > >> 
> > >> You don't have to enable the metadata if you don't want to use it,
> > >> it's
> > >> an option :)
> > > 
> > > OK, _that_ argument needs to be stomped out.  It had been used before,
> > > and it was a deliberate scam.  There is no such thing as optional
> > > kernel interface, especially when udev/dbus/systemd crowd is nearby. 
> > > We'd been through that excuse before; remember how devtmpfs was
> > > pushed in as "optional"?
> > > 
> > > This is a huge red flag.  On the level of "I need your account
> > > information to transfer $200M you might have inherited from my
> > > deceased client".
> > > 
> > > Just to recap how it went the last time around: Kay kept pushing his
> > > piece of code into the tree, claiming that it was optional, that
> > > nobody who doesn't like it has to enable it, so what's the problem? 
> > > OK, in it went.  And pretty soon udev (maintained by the same...
> > > meticulously honorable person) had stopped working on the kernels
> > > that didn't have that enabled.
> > > 
> > > We had been there before.  To paraphrase another... meticulously
> > > honorable person, "if you didn't want something relied upon, why have
> > > you put it into the kernel?" Said person is on the record as having
> > > no problem whatsoever with adding dependencies to the bottom of
> > > userland stack.
> > 
> > It appears that, if kdbus is merged, upstream udev may end up requiring
> > it:
> > 
> > http://lists.freedesktop.org/archives/systemd-devel/2014-May/019657.html
> > 
> > Grumble.
> 
> Honestly, I think that tightly coupling systemd and udev to certain kernel 
> versions in lock step is crap.

Where do you see that happening?

> That you require some minimum version after some reasonable time, sure. 
> But in lockstep? Seriously.

Has that happened in the past?  Look at the minimum requirements of
systemd/udev today, something like the 3.7 kernel release, many years
old.

> I certainly do not want a broken system just cause I have to load an older 
> kernel version for some reason.

No one does.  But, work with your distribution if you end up with
something like this.  Remember, the goal is that you can always run
newer kernels on older userspace, as that is something that we kernel
developers can enforce.  Userspace programs have other requirements /
communities, it's up to them to decide what their oldest kernel version
they wish to support.  Hint, even glibc makes these kinds of
requirements, it's nothing new at all here, so why is this even an
issue?

> And yes, I think its good not to force just about any userspace idea into 
> the kernel.

Do you have any technical objections to the patch as proposed?

thanks,

greg k-h