[elrepo] video4linux on CentOS 5 2.6.18-128.4.1.el5xen - module not found

[Phil Perry]

Philippe wrote:
> hello,
> 

Hi Philippe,

> I'm running on centos5.3 with a xen kernel
> 
>     [root at aberlour]# uname -a
>     Linux aberlour.wehowski.net 2.6.18-128.4.1.el5xen #1 SMP Tue Aug 4 21:33:24 
> EDT 2009 i686 athlon i386 GNU/Linux
> 
> 
> I installed elrepo to use my webcam(S).
> 
> the package kmod-video4linux-xen is really installed:
> 
> 	[root at aberlour]# rpm -qa|grep video
> 	kmod-video4linux-xen-0.0-5.20090615.el5.elrepo
> 
> but when I "modprobe gspca_main" I've got.
> 
> 	[root at aberlour]# modprobe gspca_main
> 	FATAL: Module gspca_main not found.
> 
> the problem seems to be that the module is located in the wrong directory
> 
> 	[root at aberlour]# locate gspca_main.ko
> 	/lib/modules/2.6.18-128.el5xen/extra/video4linux/gspca_main.ko
> 

The package is built against the base kernel (2.6.18-128) so will be 
installed to 
/lib/modules/2.6.18-128.el5xen/extra/video4linux/gspca_main.ko as you note.

> instead of: 
> 	/lib/modules/2.6.18-128_.4.1._el5xen/extra/video4linux/gspca_main.ko
> 

The weak-modules script will then link any modules with comply to the 
kABI in /weak-updates for that kernel. Can you please show the contents 
of /lib/modules/2.6.18-128.4.1.el5xen/weak-updates/video4linux/

If the module is not present (not weak-linked) then that means the kABI 
for that particular kernel is broken for that module.

I don't have an xen kernels installed to test, but I don't see any kABI 
breakage on a regular (non-xen) 2.6.18-128.4.1.el5 kernel.

> I tried to link 
> 	/lib/modules/2.6.18-128_.4.1._el5xen/extra
> to 
> 	/lib/modules/2.6.18-128.el5xen/extra
> and run a depmod. 
> 
> But I got an error message 
> 	[root at aberlour]# modprobe gspca_main
> 	FATAL: Error inserting gspca_main (/lib/modules/2.6.18-128.4.1.el5xen/extra/video4linux/gspca_main.ko): Invalid module format
> 
> 
> 
> I tried to connect my webcam on another computer running the same kernel _WITHOUT _xen. 
> Using ELRepo it works like a charm.
> 
> Any idea ?

It does look like an issue with the xen kernel maybe breaking the kABI. 
Out of interest could you try booting the original EL5.3 xen kernel 
(2.6.18-128) and see if it works on that?

> 
> Best regards 
> Philippe
> 
>