Re: [PATCH v2 11/12] driver: Google EFI SMI

From: Greg KH
Date: Mon Mar 14 2011 - 16:54:40 EST


On Mon, Mar 14, 2011 at 01:01:50PM -0700, Mike Waychison wrote:
> On Mon, Mar 14, 2011 at 8:47 AM, Greg KH <greg@xxxxxxxxx> wrote:
> > On Fri, Mar 11, 2011 at 05:43:53PM -0800, Mike Waychison wrote:
> >> The "gsmi" driver bridges userland with firmware specific routines for
> >> accessing hardware.
> >
> > As with the other driver in this series, what keeps this driver from
> > being loaded on hardware that does not support this functionality?  If
> > it is loaded, will it cause bad things to happen?
>
> gsmi itself is better guarded than the memconsole driver that the x86
> maintainers objected to.
>
> It relies on keying off of a couple different strings, looking for
> "GOOGLE" as either the OEM ID in the FADT table, or "Google, Inc." as
> the board vendor. We further discriminate whether the driver should
> load (it doesn't apply to all of our boards) with a couple other
> checks. See gsmi_system_valid(). I've added a comment to the patch
> description indicating this for the upcoming v3 send-out.

Ok, fair enough. I'm guessing that you have tried testing the module by
loading it in a machine where this doesn't work?

> > Also, what causes it to be loaded on hardware that needs it?  There
> > should be some MODULE_DEVICE_TABLE somewhere in this thing to cause it
> > to be autoloaded?
>
> I don't know if there is a good way to have this guy autoloaded, but
> that's probably fine. We will likely compile it in as a built-in or
> adjust our userland to have the module loaded. We use it on all
> machines we've been building for the last 4-5 years, and a table of
> device IDs would just contain a list of a bunch of parts that aren't
> really google-specific.

What's wrong with using DMI strings? Are there going to be that many
different ones of them here?

thanks,

greg k-h
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