Re: PCMCIA product id strings -> hashes generation at compilation time? [Was: Re: [patch 14/38] pcmcia: id_table for wavelan_cs]

From: Greg KH
Date: Tue Mar 08 2005 - 19:43:29 EST


On Wed, Mar 09, 2005 at 12:16:36AM +0100, Dominik Brodowski wrote:
> > Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx> wrote:
> > >
> > > Most pcmcia devices are matched to drivers using "product ID strings"
> > > embedded in the devices' Card Information Structures, as "manufactor ID /
> > > card ID" matches are much less reliable. Unfortunately, these strings cannot
> > > be passed to userspace for easy userspace-based loading of appropriate
> > > modules (MODNAME -- hotplug), so my suggestion is to also store crc32 hashes
> > > of the strings in the MODULE_DEVICE_TABLEs, e.g.:
> > >
> > > PCMCIA_DEVICE_PROD_ID12("LINKSYS", "E-CARD", 0xf7cb0b07, 0x6701da11),
> >
> > What is the difficulty in passing these strings via /sbin/hotplug arguments?
>
> The difficulty is that extracting and evaluating them breaks the wonderful
> bus-independent MODNAME implementation for hotplug suggested by Roman Kagan
> ( http://article.gmane.org/gmane.linux.hotplug.devel/7039 ), and that these
> strings may contain spaces and other "strange" characters. The latter may be
> worked around, but the former cannot. /etc/hotplug/pcmcia.agent looks really
> clean because of this MODNAME implementation:

I think that MODNAME should be replaced with MODALIAS, but that's a
different email thread...

Anyway, hashes are icky, I still don't see why using the string as
module aliases, and fixing up modprobe to handle spaces in module
aliases wouldn't work out easier.

thanks,

greg k-h
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