From: Bjorn Helgaas <bjorn.helgaas@hp.com>
To: Kay Sievers <kay.sievers@vrfy.org>
Subject: Re: char/tpm: tpm_infineon no longer loaded for HP 2510p laptop
Date: Fri, 3 Oct 2008 16:01:30 -0600
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On Friday 22 August 2008 06:43:05 am Kay Sievers wrote:
> On Fri, 2008-08-22 at 06:06 -0600, Bjorn Helgaas wrote:
> > Since PNP currently doesn't generate any uevents or modalias files,
> > I expect that a non-ACPI system will be unable to autoload modules
> > for ISAPNP or PNPBIOS devices.  Right?
> 
> They do create events, but without modalias. The shell script hack,
> which udev runs, will make the event behave like it contained one.

I'm finally looking at this again; sorry for the long hiatus.  I'm
working on a patch to add PNP uevent support, modalias sysfs files
for PNP, and file2alias.c changes to match, and I just want to
make sure I'm understanding this correctly.

Before your file2alias.c changes[1], I think we generated this:
    alias pnp:dPNP0500* 8250_pnp

We relied on the udev shell hack to run "modprobe -a pnp:dPNP0500"
based on the contents of /sys/bus/pnp/devices/00:05/id.

With your file2alias.c changes, we now generate this:
    alias acpi*:PNP0500:* 8250_pnp
    alias pnp:dPNP0500* 8250_pnp

On ACPI systems, this works fine because "acpi*:PNP0500:*" matches
the ACPI-generated uevents like:
    MODALIAS=acpi:PNP0501:PNP0500:

We can load 8250_pnp without relying on the udev shell hack
*on ACPI systems*.

I thought the object of your file2alias.c changes was to remove the
need for the udev shell hack, but don't we still require it on
non-ACPI systems because they won't emit the ACPI uevents?

Bjorn

[1] http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=22454cb99fc39f2629ad06a7eccb3df312f8830e
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=5e4c6564c95ce127beeefe75e15cd11c93487436
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