Re: [gentoo-user] Beta test Gentoo with mdev instead of udev; version 5

[Pandu Poluan]

On Mar 21, 2012 2:52 AM, <covici@××××××××××.com> wrote:
>
> Daddy <daddy@×××××××××××××××××××××.com> wrote:
>
> > On March 11, 2012 at 5:09 AM Walter Dnes <waltdnes@××××××××.org> wrote:
> >
> > >   This revision makes 2 changes...
> > >
> > > A) The removal of udev is now standard instead of optional.  udev-181
> > > and higher will be pulling in kmod, and anything else that kmod
depends
> > > on.  Removing udev will avoid unnecessary cruft on your machine.
> > >
> > > B) Splitting up step 3) into 3a) and 3b) for greater clarity as
> > > requested in user feedback.
> > >
> > >   The usual warnings apply...
> > > * this is a beta
> > > * use a spare test machine
> > > * if you don't follow the instructions correctly, the result might be
> > >   an unbootable linux
> > > * even if you do follow instructions, the result might be an
unbootable
> > >   linux
> > >
> > >
> > > 1) Set up your kernel to support and automount a devtmpfs filesystem
at
> > >    /dev
> > >
> > > * If you prefer to edit .config directly, set
> > >   CONFIG_DEVTMPFS=y and CONFIG_DEVTMPFS_MOUNT=y
> > >
> > > * If you prefer "make menuconfig", the route is as shown below.  Note
> > >   that the "Autount devtmpfs..." option won't appear until you enable
> > >   "Maintain a devtmpf..." option.
> > >
> > > make menuconfig
> > >   Device Drivers  --->
> > >     Generic Driver Options  --->
> > >       [*] Maintain a devtmpfs filesystem to mount at /dev
> > >       [*]   Automount devtmpfs at /dev, after the kernel mounted the
> > rootfs
> > >
> > >   Once you've made the changes, rebuild the kernel.
> > >
> > >
> > > 2) Set up for emerging busybox.  busybox requires the "mdev" flag in
> > > this situation.  The "static" flag is probably also a good idea.  In
> > > file /etc/portage/package.use add the line
> > >
> > > sys-apps/busybox static mdev
> > >
> > >    Now, "emerge busybox"
> > >
> > >
> > > 3 a) Create /sbin/linuxrc containing at least
> > >
> > > #!/bin/busybox ash
> > > mount -t proc proc /proc
> > > mount -t sysfs sysfs /sys
> > > exec /sbin/init
> > >
> > >   This should be enough for most users.  If you have an unusual setup,
> > > you may need additional stuff in there.  Remember to
> > > "chmod 744 /sbin/linuxrc" to make it executable.
> > >
> > >  In the bootloader "append" line, include "init=/sbin/linuxrc".  If
> > > you're using lilo remember to re-run lilo to implement the changes.
 If
> > > you're using another bootloader, make the equivalant initialization.
> > >
> > >
> > > 4) Remove udev from the services list, and replace it with mdev.  Type
> > >    the following 2 commands at the command line
> > > rc-update del udev sysinit
> > > rc-update add mdev sysinit
> > >
> > >
> > > 5) reboot to your new kernel.  You're now running without using udev.
> > >
> > >
> > > 6) Remove udev as per the following instructions...
> > >
> > > * execute the following command at the commandline
> > > emerge --unmerge sys-fs/udev
> > >
> > > * In file /atc/portage/package.mask, append the line
> > > sys-fs/udev
> > >   Create the file if it doesn't already exist.  You now have a totally
> > > udev-free machine
> > >
> > > --
> > > Walter Dnes <waltdnes@××××××××.org>
> > >
> >
> > Having personally long considered Lennart Poettering a 'spawn of the
devil'
> > my question is ... is this your reaction to systemd?
> >
> > One minor typo to point out:
> >
> > /atc/portage/package.mask should be /etc/portage/package.mask
> >
> > I just joined this list last week, but might consider sacrificing some
> > hardware to join your endeavor if you need more testers.
> OK, I am not seeing mdev in the portage tree -- I would like to learn
> more about this before I take the plunge.  So where do I get it and does
> it create the appropriate device nodes, etc?
>

The creation of device nodes mostly are done by the devtmpfs of the kernel.
I recommend the linuxrc to look like this :

#!/bin/busybox ash
mount -t proc proc /proc
mount -t sysfs sysfs /sys
echo /bin/mdev > /proc/sys/kernel/hotplug
/bin/mdev -s
exec /sbin/init

Before booting, ensure /bin/mdev exists and is a symlink to /bin/busybox.

The rest, just follow the steps outlined by waltdnes

Rgds,