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Old 10-12-2011, 04:40 AM
"Walter Dnes"
 
Default Suggestion for getting rid of udev

Hi all

Recently, there was a firestorm on the gentoo-user list over the idea
that udev would eventually require /usr to be on the same physical
parition as /, or else use initramfs, which is its own can of worms. I'm
not a programmer, let alone a developer. Rather than merely ranting, I
went and searched for an alternative.

Forking udev is probably not an option. The udev lead developer is a
Redhat employee, and his direction seems to be to drag everybody in
Redhat's direction. Our community doesn't have Redhat's billions.

The other option is to drop udev entirely. As an example, I suggest
looking at Alpine Linux http://alpinelinux.org/ It's a lightweight
server-oriented distro. It uses busybox's mdev instead of udev, and
some other mdev substitutes in place of standard packages. It uses
openrc. Furthermore, "previous versions of Alpine were based on Gentoo"
as per http://wiki.alpinelinux.org/wiki/Creating_an_Alpine_package so
there should be no problem with us borrowing back from Alpine.

The only reason Alpine isn't usuable for regular users right now is
that it's built with uclibc, which will break closed-source binary blobs
(e.g. Flash and Acrobat and many video card drivers). I'm not a
developer or programmer, so correct me if I'm wrong, but it shouldn't be
difficult to replace uclibc with the standard library, and build away.

Another option is to take the current Gentoo setup, drop udev and
use mdev in the same manner as Alpine uses it. In case anyone asks,
auto mounting should still be possible. Attached is an excerpt from
/var/log/messages from a basic Alpine install. The kernel messages were
generated when I inserted a USB key into a usb jack.

--
Walter Dnes <waltdnes@waltdnes.org>
Oct 9 13:46:00 e521 kern.info kernel: [10714.105621] usb 2-8: new high speed USB device using ehci_hcd and address 4
Oct 9 13:46:00 e521 kern.info kernel: [10714.241353] usb 2-8: New USB device found, idVendor=13fe, idProduct=1e00
Oct 9 13:46:00 e521 kern.info kernel: [10714.241357] usb 2-8: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Oct 9 13:46:00 e521 kern.info kernel: [10714.241360] usb 2-8: Product: Patriot Memory
Oct 9 13:46:00 e521 kern.info kernel: [10714.241362] usb 2-8: Manufacturer:
Oct 9 13:46:00 e521 kern.info kernel: [10714.241364] usb 2-8: SerialNumber: 078215A302CF
Oct 9 13:46:00 e521 kern.info kernel: [10714.244241] scsi4 : usb-storage 2-8:1.0
Oct 9 13:46:01 e521 kern.notice kernel: [10715.279753] scsi 4:0:0:0: Direct-Access Patriot Memory PMAP PQ: 0 ANSI: 0 CCS
Oct 9 13:46:02 e521 kern.notice kernel: [10715.930991] sd 4:0:0:0: [sdb] 31326208 512-byte logical blocks: (16.0 GB/14.9 GiB)
Oct 9 13:46:02 e521 kern.notice kernel: [10715.931980] sd 4:0:0:0: [sdb] Write Protect is off
Oct 9 13:46:02 e521 kern.debug kernel: [10715.931983] sd 4:0:0:0: [sdb] Mode Sense: 23 00 00 00
Oct 9 13:46:02 e521 kern.err kernel: [10715.931986] sd 4:0:0:0: [sdb] Assuming drive cache: write through
Oct 9 13:46:02 e521 kern.err kernel: [10715.935986] sd 4:0:0:0: [sdb] Assuming drive cache: write through
Oct 9 13:46:02 e521 kern.info kernel: [10715.981381] sdb: sdb1
Oct 9 13:46:02 e521 kern.err kernel: [10715.986028] sd 4:0:0:0: [sdb] Assuming drive cache: write through
Oct 9 13:46:02 e521 kern.notice kernel: [10715.986035] sd 4:0:0:0: [sdb] Attached SCSI removable disk
 
Old 10-12-2011, 05:05 AM
Zac Medico
 
Default Suggestion for getting rid of udev

On 10/11/2011 09:40 PM, Walter Dnes wrote:
> Hi all
>
> Recently, there was a firestorm on the gentoo-user list over the idea
> that udev would eventually require /usr to be on the same physical
> parition as /, or else use initramfs, which is its own can of worms. I'm
> not a programmer, let alone a developer. Rather than merely ranting, I
> went and searched for an alternative.

Are you aware of the simple linuxrc approach that I suggested here?

http://archives.gentoo.org/gentoo-dev/msg_20749880f5bc5feda141488498729fe8.xml

--
Thanks,
Zac
 
Old 10-12-2011, 05:32 AM
Nathan Phillip Brink
 
Default Suggestion for getting rid of udev

On Wed, Oct 12, 2011 at 12:40:23AM -0400, Walter Dnes wrote:
> Hi all
>
> Recently, there was a firestorm on the gentoo-user list over the idea
> that udev would eventually require /usr to be on the same physical
> parition as /, or else use initramfs, which is its own can of worms. I'm
> not a programmer, let alone a developer. Rather than merely ranting, I
> went and searched for an alternative.
...
>
> Another option is to take the current Gentoo setup, drop udev and
> use mdev in the same manner as Alpine uses it. In case anyone asks,
> auto mounting should still be possible. Attached is an excerpt from
> /var/log/messages from a basic Alpine install. The kernel messages were
> generated when I inserted a USB key into a usb jack.

Seeing from the prior conversations here (sorry for lack of citation)
and
http://lists.busybox.net/pipermail/busybox/2011-September/076710.html
, I suspect that the root problem isn't with udev itself but with the
udev rules.

The magic which makes automatic userspace configuration possible is in
the udev rules and makes udev appear to be the problem. For example,
if you switch to mdev currently, you will notice that X11's device
autodetection doesn't work so well. (At least for me, X11's
autodetection magically works for detecting input devices with udev
but not with mdev). It is concievable that you could develop a
parallel database of mdev-compatible rules and even let packages
install rules specific to themselves (with modification to mdev
http://lists.busybox.net/pipermail/busybox/2011-September/076666.html
). With these sorts of things, you might figure out a way to make
X11's device autoconfiguration work or perform other device
initialization tasks. But at the same time, you have a good chance of
accidentally introducing a reliance on libraries/programs installed to
/usr. This latter problem is the issue, deciding how much software
should have --prefix=/ versus the normal --prefix=/usr.

You can already try out what using mdev instead of udev is like in
Gentoo. Just add `sys-apps/busybox mdev' to /etc/portage/package.use,
remerge busybox. You must be sure to be using busybox-1.92.2 or later
for bug #83301.

# rc-update add mdev sysinit
# rc-update del udev sysinit

But be 'ware that this isn't guaranteed to provide a successful boot
;-).

> Oct 9 13:46:00 e521 kern.info kernel: [10714.105621] usb 2-8: new high speed USB device using ehci_hcd and address 4
> Oct 9 13:46:00 e521 kern.info kernel: [10714.241353] usb 2-8: New USB device found, idVendor=13fe, idProduct=1e00
> Oct 9 13:46:00 e521 kern.info kernel: [10714.241357] usb 2-8: New USB device strings: Mfr=1, Product=2, SerialNumber=3
> Oct 9 13:46:00 e521 kern.info kernel: [10714.241360] usb 2-8: Product: Patriot Memory
> Oct 9 13:46:00 e521 kern.info kernel: [10714.241362] usb 2-8: Manufacturer:
> Oct 9 13:46:00 e521 kern.info kernel: [10714.241364] usb 2-8: SerialNumber: 078215A302CF
> Oct 9 13:46:00 e521 kern.info kernel: [10714.244241] scsi4 : usb-storage 2-8:1.0
> Oct 9 13:46:01 e521 kern.notice kernel: [10715.279753] scsi 4:0:0:0: Direct-Access Patriot Memory PMAP PQ: 0 ANSI: 0 CCS
> Oct 9 13:46:02 e521 kern.notice kernel: [10715.930991] sd 4:0:0:0: [sdb] 31326208 512-byte logical blocks: (16.0 GB/14.9 GiB)
> Oct 9 13:46:02 e521 kern.notice kernel: [10715.931980] sd 4:0:0:0: [sdb] Write Protect is off
> Oct 9 13:46:02 e521 kern.debug kernel: [10715.931983] sd 4:0:0:0: [sdb] Mode Sense: 23 00 00 00
> Oct 9 13:46:02 e521 kern.err kernel: [10715.931986] sd 4:0:0:0: [sdb] Assuming drive cache: write through
> Oct 9 13:46:02 e521 kern.err kernel: [10715.935986] sd 4:0:0:0: [sdb] Assuming drive cache: write through
> Oct 9 13:46:02 e521 kern.info kernel: [10715.981381] sdb: sdb1
> Oct 9 13:46:02 e521 kern.err kernel: [10715.986028] sd 4:0:0:0: [sdb] Assuming drive cache: write through
> Oct 9 13:46:02 e521 kern.notice kernel: [10715.986035] sd 4:0:0:0: [sdb] Attached SCSI removable disk

Unless if I'm missing something, those messages _always_ show up even
if udev or mdev haven't been invoked.

--
binki

Look out for missing or extraneous apostrophes!
 
Old 10-12-2011, 07:05 AM
Michał Górny
 
Default Suggestion for getting rid of udev

On Wed, 12 Oct 2011 00:40:23 -0400
"Walter Dnes" <waltdnes@waltdnes.org> wrote:

> The other option is to drop udev entirely. As an example, I suggest
> looking at Alpine Linux http://alpinelinux.org/ It's a lightweight
> server-oriented distro. It uses busybox's mdev instead of udev, and
> some other mdev substitutes in place of standard packages. It uses
> openrc. Furthermore, "previous versions of Alpine were based on
> Gentoo" as per
> http://wiki.alpinelinux.org/wiki/Creating_an_Alpine_package so there
> should be no problem with us borrowing back from Alpine.

Goodbye desktop users then.

We recently dropped HAL. Now all the magic that was done by HAL (and
required udev anyway) is done through udev directly. Dropping udev =
dropping it all. This means that no *kit would work anymore, xorg will
require explicit configuration, bluez may not work anymore as well.

--
Best regards,
Michał Górny
 
Old 10-12-2011, 07:08 AM
Markos Chandras
 
Default Suggestion for getting rid of udev

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

On 10/12/11 05:40, Walter Dnes wrote:
> Hi all
>
> The other option is to drop udev entirely. As an example, I
> suggest looking at Alpine Linux http://alpinelinux.org/ It's a
> lightweight server-oriented distro. It uses busybox's mdev instead
> of udev, and some other mdev substitutes in place of standard
> packages. It uses openrc. Furthermore, "previous versions of
> Alpine were based on Gentoo" as per
> http://wiki.alpinelinux.org/wiki/Creating_an_Alpine_package so
> there should be no problem with us borrowing back from Alpine.
>
This is a joke right? All the desktop "infrastructure" depends on
that. Are you suggesting to make Gentoo an embedded/server only distro?

- --
Regards,
Markos Chandras / Gentoo Linux Developer / Key ID: B4AFF2C2
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Old 10-12-2011, 01:09 PM
"Walter Dnes"
 
Default Suggestion for getting rid of udev

On Wed, Oct 12, 2011 at 05:32:05AM +0000, Nathan Phillip Brink wrote

> You can already try out what using mdev instead of udev is like in
> Gentoo. Just add `sys-apps/busybox mdev' to /etc/portage/package.use,
> remerge busybox. You must be sure to be using busybox-1.92.2 or later
> for bug #83301.

Did you mean busybox-1.19.2? That's the latest ebuild in
/usr/portage, and it's still ~amd64 (~everything for that matter).

> # rc-update add mdev sysinit
> # rc-update del udev sysinit
>
> But be 'ware that this isn't guaranteed to provide a successful boot
> ;-).

Thanks for the idea. I have a spare box kicking around that I can try
it on.

--
Walter Dnes <waltdnes@waltdnes.org>
 
Old 10-12-2011, 01:09 PM
"Walter Dnes"
 
Default Suggestion for getting rid of udev

> Goodbye desktop users then.
>
> We recently dropped HAL. Now all the magic that was done by HAL (and
> required udev anyway) is done through udev directly.

My system worked just fine before HAL was introduced, thank you. I
always had sys-apps/hal and sys-apps/dbus in /etc/portage/package.mask
and my system continued to work just fine, thank you. Given the great
HAL fiasco, the fact that HAL has been incorporated into udev is yet one
more reason for dropping udev <G>.

--
Walter Dnes <waltdnes@waltdnes.org>
 
Old 10-12-2011, 01:10 PM
"Walter Dnes"
 
Default Suggestion for getting rid of udev

On Tue, Oct 11, 2011 at 10:05:15PM -0700, Zac Medico wrote

> Are you aware of the simple linuxrc approach that I suggested here?
>
> http://archives.gentoo.org/gentoo-dev/msg_20749880f5bc5feda141488498729fe8.xml

Thanks for the pointer. I've got a spare box kicking around that I'll
try this on. I really do want it to work.

--
Walter Dnes <waltdnes@waltdnes.org>
 
Old 10-12-2011, 01:26 PM
Rich Freeman
 
Default Suggestion for getting rid of udev

On Wed, Oct 12, 2011 at 12:40 AM, Walter Dnes <waltdnes@waltdnes.org> wrote:
> *Forking udev is probably not an option. *The udev lead developer is a
> Redhat employee, and his direction seems to be to drag everybody in
> Redhat's direction. *Our community doesn't have Redhat's billions.

We should note that RedHat is already spending their billions to make
dracut smarter, and if initramfs is good enough for RHEL then it
should be good enough for us if somebody just has to have /usr on a
separate device and needs some of the fancier udev rules to work on
boot. For those who don't need dracut there was already a stated
desire to provide a simplified initramfs. And, for less complex
setups, you don't need it at all.

My concern with something like dropping udev is that it would make us
different from every other desktop distro out there. I'm not aware of
any distro packaging Gnome/KDE without udev. Not having Redhat's
billions to me is a good reason to try to do things the same way that
Redhat does them - so that we're not re-inventing the wheel.

Gentoo is still a fairly meta distro and if users want to remove udev
they probably can do it without a great deal of hassle if they don't
want hot more hotplugish experience and don't use the big desktop
environments. It just doesn't make sense to make that a default. In
the same way I don't mind a list of CFLAGS that spans 3 lines but I'd
never advocate putting that into the default make.conf.

Rich
 
Old 10-12-2011, 04:28 PM
Canek Pelez Valds
 
Default Suggestion for getting rid of udev

On Wed, Oct 12, 2011 at 6:09 AM, Walter Dnes <waltdnes@waltdnes.org> wrote:
>> Goodbye desktop users then.
>>
>> We recently dropped HAL. Now all the magic that was done by HAL (and
>> required udev anyway) is done through udev directly.
>
> *My system worked just fine before HAL was introduced, thank you. *I
> always had sys-apps/hal and sys-apps/dbus in /etc/portage/package.mask
> and my system continued to work just fine, thank you.

This is not about *your* system, it's about the general Gentoo
community systems. And in most cases, the functionality that mdev
provides is not even a fraction of what udev can do, like it or not.

I have a pair of bluetooth headphones; I turn them up and set them to
pair with something, and gnome-shell in GNOME 3 right away asks me if
it's OK to pair with them. I say yes, and the headphones are
immediately available in the desktop; thanks to PulseAudio, I can
transfer all my apps (or only some of them) to the headphones, without
even needing to pause the streams.

All of this without a single modification to a config file. It just
works. And that is thanks to udev (among several other pieces of the
stack).

mdev is designed for embedded systems (like busybox). By design it
cannot handle of the cases that udev handles, and so it is not suited
for a general purpose distribution like Gentoo. If you wan to try to
use it, that's your right of course. But don't ask the Gentoo devs to
do the work for you; do it yourself. And be aware that anyway the devs
will choose to stick with udev (like many have already said), because
they have to think about the general case, not an arbitrary particular
case.

Just the .02 ${CURRENCY} from an old Gentoo user happy with systemd,
dracut, udev, dbus, GNOME 3, and other really cool new technologies.

Regards.
--
Canek Pelez Valds
Posgrado en Ciencia e Ingeniera de la Computacin
Universidad Nacional Autnoma de Mxico
 

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