linux-kernel - Re: MODULE_DEVICE_TABLE(isapnp, ...) does nothing

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Date:	Wed, 25 Nov 2009 18:17:45 +0100
From:	Ondrej Zary <linux@...nbow-software.org>
To:	Kay Sievers <kay.sievers@...y.org>
Cc:	Rusty Russell <rusty@...tcorp.com.au>,
	Takashi Iwai <tiwai@...e.de>, linux-kernel@...r.kernel.org,
	Jon Masters <jonathan@...masters.org>,
	Jaroslav Kysela <perex@...ex.cz>, Greg KH <gregkh@...e.de>
Subject: Re: MODULE_DEVICE_TABLE(isapnp, ...) does nothing

On Tuesday 24 November 2009 09:53:51 Kay Sievers wrote:
> On Mon, Nov 23, 2009 at 22:51, Rusty Russell <rusty@...tcorp.com.au> wrote:
> > On Mon, 23 Nov 2009 07:10:22 pm Takashi Iwai wrote:
> >> At Mon, 23 Nov 2009 13:59:53 +1030, Rusty Russell wrote:
> >> > Two things are required:
> >> > 1) Modify file2alias to add aliases for isapnp.  This is pretty easy.
> >> > 2) Expose the isapnp devices in sysfs where udev will match them up
> >> >    (/sys/bus/isa/devices/<dev>/modalias I guess?)
> >>
> >> There is non-pnp ISA bus, so I'm afraid "isa" may conflict.
> >> I suppose "isapnp" would be a safer choice.
> >
> > Without pnp, I don't think you can enumerate the ISA bus. Hence I chose
> > "isa:" in the hope that udev would "just work" if isapnp created the
> > modalias under /sys/bus/isa...
> >
> > But Kay says there's a pnp bus (who knew?).  I don't know what he means
> > by unfixable aliases tho, since it's all in the kernel source so we can
> > change it at any time?
>
> Here's a bit of the background:
>
> The aliases in the modules can only match a single value, but PNP
> devices often have vendor specific IDs and usual IDs describing the
> function.
>
> Like here, where the interesting ID is only the second one of the two
> for a single device:
>   $ grep . /sys/bus/pnp/devices/*/id
>   /sys/bus/pnp/devices/00:09/id:LEN0006
>   /sys/bus/pnp/devices/00:09/id:PNP0f13

It's the same for my RTL8019 card:
$ grep . /sys/bus/pnp/devices/*/id
/sys/bus/pnp/devices/01:01.00/id:RTL8019
/sys/bus/pnp/devices/01:01.00/id:PNP80d6

and it works with this (which could be easily generated from the current ne 
module, I think):
alias pnp:dPNP80d6* ne

This works fine too:
alias pnp:dRTL8019* ne
alias pnp:dPNP80d6* ne

> So the kernel device would need to compose a "modalias" string with
> all IDs in a single line. But the in-module aliases can unfortunately
> match only on a single value, like:
>   alias pnp:dPNP0700* floppy
>
> For that reason, a while ago udev switched to acpi aliases entirely,
> and dropped all pnp: usage. The acpi aliases can handle multi-values
> just fine with single strings like:
>   $ cat /sys/bus/acpi/devices/LEN0006:00/modalias
>   acpi:LEN0006:PNP0F13:
>
>   alias acpi*:PNP0700:* floppy
>
> Udev does not use any pnp: or /sys/bus/pnp/ values since a while. But
> there might be still distros who use the (broken) pnp: aliases and
> ship the (also broken) shell scripts to iterate over the sysfs devices
> and call modprobe for all they find.
>
> Thanks,
> Kay



-- 
Ondrej Zary
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