Re: [PATCH V3 2/4] scsi: storvsc: Properly support Fibre Channel devices

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Fri, 2015-12-18 at 09:49 +0100, Hannes Reinecke wrote:
> What I would like to see is a clear separation here:
> - Disable FC disk handling if FC attributes are not configured
> - Add a module parameter allowing to disable FC attributes even if 
> they are compiled in. Remember: this is a virtualized guest, and 
> people might want so save kernel memory wherever they can. So always 
> attaching to the fc transport template will make them very unhappy.
> Alternatively you could split out FC device handling into a separate 
> driver, but seeing the diff that's probably overkill.

I don't quite see how this can be a module parameter: the
fc_transport_class is pulled in by symbol references.  They won't go
away whether a module parameter is zero or one.  The only way to get
the module not to link with a transport class is to have it not use the
symbols at compile time (either because they're surrounded by an #ifdef
or with an if() which the compiler evaluates at compile time to zero). 
 In userspace you get around this with introspection and dlopen, but I
don't think we have that functionality in the kernel.

James