Can't load vboxdr module into realtime kernel

[Rafael Vega]

$ sudo modprobe vboxdrv
FATAL: Error inserting vboxdrv (/lib/modules/3.2.0-23-realtime/updates/dkms/vboxdrv.ko): Unknown symbol in module, or unknown parameter (see dmesg)

$ dmesg
...
[ 2600.875176] vboxdrv: Unknown symbol down_write (err 0)
[ 2600.875208] vboxdrv: Unknown symbol up_write (err 0)
[ 2600.875303] vboxdrv: Unknown symbol down_read (err 0)
[ 2600.875373] vboxdrv: Unknown symbol up_read (err 0)

Also, when compiling vboxdrv using the same real time kernel, I get warnings about non-existent symbols "down_write", "up_write", "up_read" and "down_read".

Switching to a lowlatency kernel is a valid workaround in my case.

[Frank Mehnert]

Which Linux distribution is that?

[Rafael Vega]

Ubuntu 12.04. Same problem with apt-get version of Virtualbox, the binary downloaded from virtualbox.org and compiled from source. (sorry it took so long to reply)

[Frank Mehnert]

Ok. So where you have the kernel package from? Because the standard Ubuntu package repository does not provide any realtime kernel.

[Rafael Vega]

I got it from the KXStudio repositories at ​http://kxstudio.sourceforge.net/KXStudio:Repositories

[Frank Mehnert]

Well, I can reproduce the build error here. However, it seems to me that these realtime packages have some problems. For instance, the header file <linux/rwsem_rt.h> is missing. To me it seems that for a RT kernel, up/down_read/write() should be replaced by the corresponding rt_* functions but there are no prototypes for these functions. So I cannot propose a patch.