[EdLUG] Module parameters are different from cmdline

[Edinburgh Linux Users Group]

On 2016.12.28 23:56, Edinburgh Linux Users Group wrote:
> Hi Roy,
> 
> After some investigation it turned out that Ubuntu packs both -
> gzipped
> initrd.img and Intel's microcode into one initrd file. That's why I
> couldn't initially extract the whole Init ramfs.
> 
> Now I see that i915.ko module is included into initrd and that
> /etc/modprobe.d actually has i915.conf with my options inside. So,
> it's
> clear now that i915 is a module and where its configuration comes
> from.
> It's also confirmed by "dmesg" output where i915 reports setting of
> the
> "dangerous options".
> 
> The weird thing now is - provided all of the facts above, the module
> still
> ignores the config. It still continues to use some default settings.
> 
> There's no other place except /etc/modprobe.d in initrd which contains
> or
> may override "enable_execlists" setting (checked by 'grepping' all of
> the
> extracted contents)
> 
> Best Regards,
> Maxim
> 
[snip]

Maxim,

I'm stretching my module loading knowledge a bit now.
There are several mechanisms for loading kernel modules.
They don't all respect module parameter settings, as you 
appear to be discovering.

How you address this for your use case with Ubuntu is
outside my experience. If you can unload the module, its trivial.
You can only do that while the module is not used though.

Having helped with identifying the problem, I'll leave it to 
someone who knows Ubuntu to point the way to a Ubuntu
solution.

The backstop is to rebuild your kernel with i915 set to =y.
Then it will respond to kernel command line parameters.

Regards,

Roy Bamford.