Re: [patch] pnp rc

["Alexander E. Patrakov" <patrakov@ums.usu.ru>]

Alexander E. Patrakov wrote:
> 1) I have to coordinate my actions with Marco d'Itri (from Debian). I 
> remember his words about the idea with aliases being modern, progressive 
> and right. The question is whether it is possible and good to apply this 
> idea to pci.rc also. I think it is, but I want to know his opinion.

(in fact what I try to do here is to test this approach on a 
well-supported PCI bus and, in the case of success, drop pnp.rc in 
favour of isapnp.rc maintained at Debian).

Found a problem with this approach. If this idea with aliases is applied 
to the PCI case, let's see what happens to a user with an Intel 
EtherExpress 100 network card and some sort of a blg bloated modular 
"distribution" kernel.

There are two official drivers for this sort of card, e100 and eepro100. 
  In order to choose one, the user currently has to blacklist the other 
by adding a line to /etc/hotplug/blacklist. Then the first 
non-blacklisted driver gets loaded.

With the approach based on the aliases (and blacklisting based on 
modprobe output, as currently done in Debian in isapnp.rc), it is 
difficult to implement. First, Debian-like solution:

	# Generate $ALIAS from the PCI ID
         MODULE=$(modprobe --show-depends -q $ALIAS | sed -e 
'$!d;s/.*\/\(.*\)\.ko .*/\1/')
         [ "$MODULE" ] || continue
	# and now check the module against the blacklist

This fails because modprobe will resolve only one of the candidate 
modules. E.g., suppose that it would (unwantedly) pick e100. I blacklist 
e100. $MODULE will still be e100, and as a result nothing will be loaded.

So we have either to ask Rusty Russel to add an option to modprobe to 
print all possible resolutions of an alias (BTW which list should this 
go to?), or implement that by grepping the output of "modprobe -c", like 
this:

# obtain $VENDOR and $DEVICE
MODULES=$(modprobe -c | grep "alias pci:v0000${VENDOR}d0000${DEVICE}" | 
grep -o '[^ ]*$')
# check against the blacklist

(yes, I know that I have to check subvendor and subdevice too).

Does this grepping sound like a good idea?

-- 
Alexander E. Patrakov


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