Jonathan Callen <jcal...@gentoo.org> wrote: > On 06/09/2016 10:00 AM, Dale wrote: > > waltd...@waltdnes.org wrote: > >> On Thu, Jun 09, 2016 at 08:16:57AM -0500, Dale wrote > >>> k...@aspodata.se wrote: > >>>> Dale: > >>>> ... > >>>>> Can a system even boot without udev? > >>>> Yes, use sys-fs/static-dev (unless you have some special boot > >>>> requirements). > >>> Well, I was talking about if udev was removed and then a reboot > >>> was done. I would think it would boot to a certain point then > >>> when whatever started and needed devices to be created in /dev, > >>> it would start failing. I suspect this would vary depending on > >>> the install as well. > >> You need *A* device-manager. You can use udev, eudev, > >> static-dev, mdev, whatever, but you need something. Mind you, > >> some software assumes or requires udev/eudev. > >> > > > > > > What I was referring to was if during this switch from udev to > > eudev, someone rebooted without any dev manager at all. In other > > words, emerge -C udev and then reboot before emerging eudev or some > > other dev manager. I suspect that would get interesting pretty > > quick. > > > > Dale > > > > :-) :-) > > > > > > Actually, you no longer need a user-space device manager at all, > unless you want to be able to access device nodes under /dev as a > user that isn't UID=0 or has CAP_DAC_OVERRIDE. The kernel provides a > devtmpfs filesystem that will have every single device node that udev > used to create (udev no longer even creates the devices -- it just > relies on devtmpfs doing so), but most of them will be owned by 0:0 > (root:root) with permissions 0600; excepting certain nodes > like /dev/null or /dev/zero, which will be owned by 0:0 with > permissions 0666. One other thing that udev does that you might rely > on is to create symlinks like /dev/disk/by-label/*, which can be used > by mount(8) if you specify LABEL=foo in /etc/fstab. The only other > things that I'm aware of udev doing is to rename network devices and > (possibly) to notify other applications of changes, somehow (but I'm > not sure that it actually does that). > > If you don't actually need any of that (you are working on an embedded > system where you only need root anyway, for instance), then you can > just use a bare devtmpfs without a device manager changing > permissions, adding links, etc.
THX for all the information. Now I understand better what (e)udev is doing. -- Regards wabe
