Dynamic Kernel Module Support (DKMS)

upnort · 06-28-2017, 07:21 PM

Anybody here using DKMS to automatically rebuild kernel modules with Slackware?

There is a slackbuild available, but I have no idea how to implement.

Today I updated the 14.2 kernel to 4.4.74. Rebuilding the VirtualBox kernel modules is on my kernel update check list and takes about a minute to do, and I wondered about using DKMS with Slackware.

At work I use other distros and DKMS is a nice help, epsecially when the maintainers of those other distros are die-hard members of the kernel-of-the-week club. Thankfully Slackware does not issue kernel updates for every oddball corner case patch, but I still wonder how to use DKMS with Slackware.

Thanks.

P.S. I notice the DKMS support has been removed in the VirtualBox vboxdrv script.

bassmadrigal · 06-28-2017, 09:56 PM

In the amdgpu-pro driver, I initially had dkms support available, however, since it added a requirement for a 3rd-party program, once I figured out how to compile the source itself, I ended up removing it (although, it wouldn't be that hard to put back in).

I've only seen a few people on the forum use dkms. I imagine part of it is because Slackware has so few kernel updates (outside of -current) and another part is that it has the potential to have files that the package manager doesn't know about. Since there is no script support when removing packages (like the doinst.sh when installing), it prevents cleaning up any files or directories created by dkms after package creation (so any kernel updates would leave orphan files if the dkms package is removed).

But I have no issues adding dkms support to amdgpu-pro, and other slackbuild maintainers may be willing as well (they may be like me and not including support since it isn't common to use it on Slackware).

chris.willing · 06-28-2017, 10:40 PM

Yes I wouldn't leave home without it. I have three external modules that are kernel version dependent so DKMS was really useful after the recent kernel update; on reboot these modules were rebuilt so that they were all able to work immediately which was very convenient (especially since nvidia was one of the modules).

To make the module rebuilding happen at boot time, I've inserted the following lines into rc.S (just after isapnp and just before kernel module scrip is run)

Code:

# Enable the DKMS autoinstaller
if [ -x /etc/rc.d/rc.dkms_autoinstaller ]; then
    /etc/rc.d/rc.dkms_autoinstaller start
fi

chris

Darth Vader · 06-30-2017, 04:22 PM

Yeah, the DKMS is amazing useful in a Slackware release, with its three kernel updates in a whooping 3 years. If even exists kernel updates...

chris.willing · 06-30-2017, 05:36 PM

So few kernel updates may not make DKMS seem so amazing if you run just one machine, but different story if you're responsible for a lab of 20+ machines.

upnort · 06-30-2017, 06:23 PM

Quote:

/etc/rc.d/rc.dkms_autoinstaller

Is this a special script you wrote for yourself?

Quote:

So few kernel updates may not make DKMS seem so amazing if you run just one machine, but different story if you're responsible for a lab of 20+ machines.

Indeed. In my original post I mentioned that Slackware is not a member of the kernel-of-the-week club. I have one physical Ubuntu 16.04 and one virtual CentOS 7 system. The almost weekly kernel updates are a tad exhausting.

I am no security expert and do not play one on TV. My cursory readings of kernel security notices indicate that while a legitimate concern, most of the kernel security flaws require unusual or esoteric circumstances to exploit. Thus most users are unaffected.

That said, I have three Slackware systems using VirtualBox. While I have my own method of updating the kernel module in an efficient manner, I started this thread with the hope that some discussion might reveal whether DKMS could be useful.

chris.willing · 06-30-2017, 06:53 PM

Quote:

Originally Posted by upnort

Is this a special script you wrote for yourself?

Although I've been using it for years, dkms was only added to SBo last December, so I had my own build script. Looking back at it now, the rc.dkms_autoinstaller is installed by the Makefile. That could be different with the current version (my build script was for version 2.2.1.2 which is quite old now).

chris

upnort · 07-04-2017, 07:07 PM

Doesn't look like much interest in the topic. I guess that's that.

chris.willing · 07-06-2017, 01:45 AM

I just emailed the maintainer with a patch to the SlackBuild so that dkms will invoke the rebuild of its modules at boot time whenever there's been a change in kernel version.

chris

upnort · 07-06-2017, 09:35 AM

Great! Slackware is not a member of the kernel-of-the-week club. Testing an updated DKMS package will be a challenge.

Also raises the question of how this will affect other SlackBuild packages, such as VirtualBox or Nvidia. For example, the VirtualBox package strips the DKMS support from the respective rc.d script.

bassmadrigal · 07-06-2017, 09:52 AM

Quote:

Originally Posted by upnort

Also raises the question of how this will affect other SlackBuild packages, such as VirtualBox or Nvidia. For example, the VirtualBox package strips the DKMS support from the respective rc.d script.

If the packages made by other SlackBuilds don't support DKMS, then nothing will be rebuilt on reboot. Those SlackBuilds would need to be rerun against the new kernel.

You could ask the package maintainers to see if they're willing to add DKMS support (probably as an optional thing with it being disabled by default -- this prevents DKMS from being listed as a required dependency for those programs).

kjhambrick · 07-07-2017, 08:48 AM

All --

This could be a useful addition to Slackware for me and the company I work for.

We've got OOO 60 remote headless boxes accessible only via SSH + PSKs.

While I don't have a specific use case, the availability of DKMS could be a godsend should we find we need to install out-of-tree modules on the remote boxes.

Almost all of these boxes are CentOS 6 but we are replacing CentOS with Slackware64 as required -- we've got a few test instances out now.

Being curious, I build the dkms-2.4.0-x86_64-1_SBo.tgz Package.

There is no longer an /etc/rc.d/rc.dkms_autoinstaller file in the Package.

Need to read a bit more ... maybe rc.dkms_autoinstaller file is no longer necessary ?

Thanks !

-- kjh

This is the content of the latest Package from SBo:

Code:

# tar -tvf dkms-2.4.0-x86_64-1_SBo.tgz

drwxr-xr-x root/root         0 2017-07-07 08:34 ./
drwxr-xr-x root/root         0 2017-07-07 08:34 etc/
drwxr-xr-x root/root         0 2017-07-07 08:34 etc/dkms/
-rw-r--r-- root/root       906 2017-05-22 11:14 etc/dkms/framework.conf
drwxr-xr-x root/root         0 2017-07-07 08:34 etc/bash_completion.d/
-rw-r--r-- root/root      2384 2017-05-22 11:14 etc/bash_completion.d/dkms
drwxr-xr-x root/root         0 2017-07-07 08:34 var/
drwxr-xr-x root/root         0 2017-07-07 08:34 var/lib/
drwxr-xr-x root/root         0 2017-07-07 08:34 var/lib/dkms/
-rw-r--r-- root/root         6 2017-05-22 11:14 var/lib/dkms/dkms_dbversion
drwxr-xr-x root/root         0 2017-07-07 08:34 usr/
drwxr-xr-x root/root         0 2017-07-07 08:34 usr/sbin/
-rwxr-xr-x root/root    139285 2017-07-07 08:34 usr/sbin/dkms
drwxr-xr-x root/root         0 2017-07-07 08:34 usr/man/
drwxr-xr-x root/root         0 2017-07-07 08:34 usr/man/man8/
-rw-r--r-- root/root     13218 2017-05-22 11:14 usr/man/man8/dkms.8.gz
drwxr-xr-x root/root         0 2017-07-07 08:34 usr/doc/
drwxr-xr-x root/root         0 2017-07-07 08:34 usr/doc/dkms-2.4.0/
-rw-r--r-- root/root        63 2017-05-22 11:14 usr/doc/dkms-2.4.0/TODO
-rw-r--r-- root/root      2828 2017-07-07 08:34 usr/doc/dkms-2.4.0/dkms.SlackBuild
-rw-r--r-- root/root       706 2017-05-22 11:14 usr/doc/dkms-2.4.0/AUTHORS
-rw-r--r-- root/root      4802 2017-05-22 11:14 usr/doc/dkms-2.4.0/README.md
-rw-r--r-- root/root     18007 2017-05-22 11:14 usr/doc/dkms-2.4.0/COPYING
drwxr-xr-x root/root         0 2017-07-07 08:34 usr/lib/
drwxr-xr-x root/root         0 2017-07-07 08:34 usr/lib/dkms/
-rwxr-xr-x root/root      1633 2017-05-22 11:14 usr/lib/dkms/dkms_autoinstaller
-rwxr-xr-x root/root      9017 2017-05-22 11:14 usr/lib/dkms/common.postinst
drwxr-xr-x root/root         0 2017-07-07 08:34 install/
-rw-r--r-- root/root       681 2017-07-07 08:34 install/slack-desc

upnort · 07-07-2017, 10:01 AM

The file /usr/lib/dkms/dkms_autoinstaller has the format of an rc file.

kjhambrick · 07-07-2017, 10:03 AM

Quote:

Originally Posted by upnort

The file /usr/lib/dkms/dkms_autoinstaller has the format of an rc file.

upnort --

Yes, I 'found' that too.

But looking at the shell script: usr/lib/dkms/common.postinst ...

It looks like it might need a little work to run on a Slackware Box ?

-- kjh

bassmadrigal · 07-07-2017, 11:30 AM

Maybe Chris would be willing to share his patch he provided to the maintainer (in case the maintainer decides to not use his patch -- or the maintainer is no longer active... the last two updates weren't done by the maintainer).