kernel linker: Overriding a driver shipped with kernel via module?

[Slawa Olhovchenkov]

On Tue, Nov 18, 2014 at 04:36:32PM -0800, John-Mark Gurney wrote:

> Slawa Olhovchenkov wrote this message on Wed, Nov 19, 2014 at 04:27 +0400:
> > On Tue, Nov 18, 2014 at 04:15:10PM -0800, John-Mark Gurney wrote:
> > 
> > > Slawa Olhovchenkov wrote this message on Tue, Nov 18, 2014 at 16:45 +0400:
> > > > On Mon, Nov 17, 2014 at 03:15:29PM -0800, Xin Li wrote:
> > > > 
> > > > > Right now one can declare version for a module by doing something like:
> > > > > 
> > > > > MODULE_VERSION(module_name, module_version);
> > > > > 
> > > > > Sometimes, it may be desirable for a vendor to release a new driver
> > > > > that overrides the driver shipped with the kernel itself.  However, it
> > > > > seems that the MODULE_VERSION facility would just refuse the module
> > > > > when preloaded with kernel.
> > > > > 
> > > > > Looking at some other vendor drivers, they are using a slightly
> > > > > different module name to overcome this limitation.  Is that the only
> > > > > way to do it?
> > > > 
> > > > I think now time to move to modulated kernel and load all drivers
> > > > currently present in GENERIC as modules (via loader.conf).
> > > 
> > > This becomes slightly more difficult for storage drivers which must
> > > be loaded at boot time so the you can mount root from it...  But yes,
> > > we are interested in methods to make it easier/more automatic for
> > > modules to be loaded to support the hardware that is present in a
> > > system...
> > 
> > When loader can load kernel -- loader can load driver module, this is
> > not Linux (but yes, loader need plugable and stackable framework for
> > access FS -- currenly booting from ZFS over gstripe not allowed).
> 
> That isn't the only issue.. another issue is identifing the correct
> kernel module(s) to load at boot... iirc, you cannot unload a kernel

At first time load all drivers, currenly present in GENERIC kernel.

> module loaded at boot time...

This is module depended. Some modules can't be unloaded (independently
of load time).