Remotely upgrading kernel: replacing devfs with udev

Hi,

*Problem
I have a number of hosts spread around the country running
the 2.6.12
kernel. I need to upgrade to 2.6.18, which requires udev to
replace
devfs. Is there any way I can prepare /dev for this upgrade
so the hosts
will boot without human interaction/booting with CD-ROM?

*Details
When I previously upgraded my own laptop a year or so ago,
this led to
the lack of certain dev-nodes upon boot (/dev/console and
/dev/null, I
believe), causing a kernel panic. I fixed that by booting
with cd-rom
and recreating the necessary nodes, as described in section
3 here:
http://ww
w.gentoo.org/doc/en/udev-guide.xml

This is of unfortunately not an option for my hosts since
the majority
don't run any form of LOM, and getting a tech to stand by
each host,
boot the Rescue-CD and do all sorts of stuff is a major
hassle.

*Possible solution
I think a possible solution may be to do the following while
the host is
still running its old kernel:

mount --bind / /mnt/point
cd /mnt/point/dev
mknod -m 660 console c 5 1
mknod -m 660 null c 1 3
cd /
umount /mnt/point

Will/should this work? If not: Any other suggestions?

Cheers,
Einar S. Idsų
-- 
gentoo-servergentoo.org mailing list

Einar S. Idsų wrote:
> Hi,
> 
> *Problem
> I have a number of hosts spread around the country
running the 2.6.12
> kernel. I need to upgrade to 2.6.18, which requires
udev to replace
> devfs. Is there any way I can prepare /dev for this
upgrade so the hosts
> will boot without human interaction/booting with
CD-ROM?

It *should* be as easy as emerging udev and rebooting. The
init scripts default 
to udev by default.

> *Details
> When I previously upgraded my own laptop a year or so
ago, this led to
> the lack of certain dev-nodes upon boot (/dev/console
and /dev/null, I
> believe), causing a kernel panic. I fixed that by
booting with cd-rom
> and recreating the necessary nodes, as described in
section 3 here:
> http://ww
w.gentoo.org/doc/en/udev-guide.xml

These initial devices likely didn't exist in the past since
devfs ran from the 
kernel and operated on a virtual filesystem. Udev works
completely different. It 
runs entirely from userland and populates a tmpfs. Until
that tmpfs is created 
and udev started, those few initial nodes are requires for
the init scripts.

> This is of unfortunately not an option for my hosts
since the majority
> don't run any form of LOM, and getting a tech to stand
by each host,
> boot the Rescue-CD and do all sorts of stuff is a major
hassle.
> 
> *Possible solution
> I think a possible solution may be to do the following
while the host is
> still running its old kernel:
> 
> mount --bind / /mnt/point
> cd /mnt/point/dev
> mknod -m 660 console c 5 1
> mknod -m 660 null c 1 3
> cd /
> umount /mnt/point
> 
> Will/should this work? If not: Any other suggestions?

Yes, this should do the trick. Although, the -m is likely
not needed. If you are 
going to use it, here's the nodes from my / (pre-udev) for
reference:

crw------- 1 root tty  5, 1 Nov 13  2005 console
crw-rw-rw- 1 root root 1, 3 Nov 13  2005 null

-- 
Andrew Gaffney                            http://dev.gentoo.or
g/~agaffney/
Gentoo Linux Developer                                  
Installer Project
Today's lesson in political correctness:      "Go
asphyxiate on a phallus"
-- 
gentoo-servergentoo.org mailing list

Andrew Gaffney wrote:
> Yes, this should do the trick. Although, the -m is
likely not needed. If
> you are going to use it, here's the nodes from my /
(pre-udev) for
> reference:
>
> crw------- 1 root tty  5, 1 Nov 13  2005 console
> crw-rw-rw- 1 root root 1, 3 Nov 13  2005 null

Thank you! I will go ahead and try this out then.

Cheers,
Einar


-- 
gentoo-servergentoo.org mailing list

Einar S. Idsų wrote:
> Andrew Gaffney wrote:
>> Yes, this should do the trick. Although, the -m is
likely not needed. If
>> you are going to use it, here's the nodes from my /
(pre-udev) for
>> reference:
>>
>> crw------- 1 root tty  5, 1 Nov 13  2005 console
>> crw-rw-rw- 1 root root 1, 3 Nov 13  2005 null
> 
> Thank you! I will go ahead and try this out then.

This worked nicely. Thanks!

Cheers,
Einar
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