How to disable DVD optical drive?

[cinux]

Is there a way to disable CD-DVD optical drive inside OpenBSD?

I used to disable it via bios menu. However I installed coreboot recently and there is no options for me to disable it. I am curious whether it is possible to disable my optical driver inside OpenBSD?

The reason I would like to disable it because my hardware got some issue, and just a little pressure to the optical drive would activate or trigger my laptop to eject it, really annoying. I don't want to take it apart either cause it make my laptop uglier and less sturdy. My workaround was tape it, but the optical drive still activate randomly.

My laptop is Thinkpad T430.

[jggimi]

Hello, and welcome!


You can disable the cd(4) driver with config(8). This will also disable kernel address randomization (KARL).

[cinux]

#2 I made changed to the kernel and boot from a bsd.newl. I check with cdio eject and it couldn't eject the disk which is a good thing. However when I press the physical button to eject disk, it still activate the CD/DVD optical drive. I think disable it within the OS doesn't disable the hardware.
Even though the problem not solved, I did learn more about OpenBSD kernel things, and it wasn't hard as I imagined.
Thank you @iggimi

Script started on Sun Jan 23 21:57:41 2022
]0;cinux@openbsd:~[32mcinux@openbsd[0m:[34m~[32m$[0m PS1=""

doas -e  config -e /bsd.new


doas (cinux@openbsd) password: 
WARNING no output file specified
OpenBSD 7.0 (GENERIC.MP) #4: Tue Jan 18 05:38:49 MST 2022
    root@syspatch-70-amd64.openbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC.MP
Enter 'help' for information
ukc> s find 40
 40 cd* at scsibus* disable target -1 lun -1 flags 0x0
ukc> exit
^D


Script done on Sun Jan 23 21:58:28 2022

dmesg

[jggimi]

Originally Posted by cinux

I think disable it within the OS doesn't disable the hardware.

The OS will ignore the device, but it seems that manual ejection is still possible without OS control.

The cd(4) man page has a reference to CDIOCPREVENT, an IOCTL designed to "Tell the drive to (prevent) manual ejection of the CD-ROM disc. Not all drives support this feature." I will guess that if you re-enabled the driver and wrote a program that issued the CDIOCPREVENT IOCTL, such a program might not stop the button from manually ejecting the device drawer.

[cinux]

Originally Posted by jggimi

The OS will ignore the device, but it seems that manual ejection is still possible without OS control.

The cd(4) man page has a reference to CDIOCPREVENT, an IOCTL designed to "Tell the drive to (prevent) manual ejection of the CD-ROM disc. Not all drives support this feature." I will guess that if you re-enabled the driver and wrote a program that issued the CDIOCPREVENT IOCTL, such a program might not stop the button from manually ejecting the device drawer.

I'm not familiar with programming except for some simple shell scripts to extract information for the status bar. I planning to learn C soon, but for now the tape tricks make it much less annoying so I might as well live with it for a little while.

And thank you a lot.

[jggimi]

This particular IOCTL is not used by any userland application in the OS, according to find(1). But once you've learned a little C you may be able to add a custom function to the cdio(1) tool for your personal use. This program's source code resides in /usr/src/usr.bin/cdio/.

[fvgit]

Originally Posted by jggimi

Hello, and welcome!


You can disable the cd(4) driver with config(8). This will also disable kernel address randomization (KARL).

There's also bsd.re-config(5) which was introduced in 7.0, allowing you to do the same thing without sacrificing KARL functionality:

Introduced /etc/bsd.re-config(5), which can be used to configure the kernel using config(8), allowing use of KARL while making changes to the GENERIC kernel.

src: https://www.openbsd.org/70.html

[jggimi]

I'd forgotten about that. Thank you!