Re: [gentoo-dev] devfs is dead, let's move on

[Martin Schlemmer]

On Thu, 2005-07-07 at 13:52 -0700, Greg KH wrote:
> On Thu, Jul 07, 2005 at 03:55:45PM +0200, Martin Schlemmer wrote:
> > On Wed, 2005-07-06 at 15:46 -0700, Greg KH wrote:
> > > Ok, now that devfs is removed from the 2.6 kernel tree[1], I think it's
> > > time to start to revisit some of the /dev naming rules that we currently
> > > are living with[2].
> > >
> > > To start with, the 061 version of udev offers a big memory savings if
> > > you use the "default" kernel name of a device[3].  If you do that, it does
> > > not create a file in its database in /dev/.udevdb/
> > >
> > > If we can move away from some of our devfs-like names, we stand to
> > > reclaim a lot of memory from everyone's machines.  As an example, if we
> > > drop all of the tty/pts/vc/vcc symlinks, and just go with the default
> > > kernel name, we save 2.5Mb of space in tempfs/ramfs.  I've done this on
> > > my machines and everything seems to work just fine (it looks like
> > > everything that was trying to use a tty node was just using the symlink
> > > anyway.)
> > >
> > > So, anyone have any objections to me changing the default udev naming
> > > scheme in this manner?
> > >
> >
> > Fine with me.  I assume we will need to keep the rcscript support for
> > those die-hard 2.4 users still, but hopefully we can eventually drop
> > that as well.
>
> What rcscript support?
>

Err, sorry, all the crap in /sbin/rc ...

> > > Next up, that loony block device naming scheme (more on that later...)
> > >
> >

> > > [3] HAL needs a patch to be able to handle this.  It's posted on the
> > >     hal development mailing lists and will be checked in real-soon-now.
> >
> > I just think we need to make sure this is in first ...
>
> The HAL patch?  It's now in HAL's cvs tree, don't know when they will do
> a new release.
>

Well, you did provide the patch, so hopefully foser or somebody else
will just add it.  Foser ping ...

> > Lastly on an unrelated note ... I have a rule:
> >
> > -----
> > # cat /etc/udev/rules.d/40-dm.rules
> > KERNEL="dm-[0-9]*", PROGRAM="/sbin/devmap_name %M %m", NAME="mapper/%c", SYMLINK="%c"
> > -----
> >
> > And in theory it should be the last rule to set the name ... however the
> > default one in 50-udev.rules overrides it, and I have to add
> > OPTIONS="last_rule"
>
> Yes.
>
> Want me to just change the default rule to yours?
>

I do not think that will work, as that is not distributed with either
udev or device-mapper, but multipath-tools (sorda silly if you ask me,
as I think it would have been more appropriate with device-mapper, but
what the hey).

Anyhow, I'll see if I can hack a patch or something up so that NAME=""
will also be seen as as a rule that 'set the name' ....


Thanks,

-- 
Martin Schlemmer
Gentoo Linux Developer, Desktop/System Team Developer
Cape Town, South Africa