ip autoconfig for PCMCIA NICs]

From: David Hinds <[email protected]>
To: Andrew Morton <[email protected]>
Cc: lkml <[email protected]>, David Woodhouse <[email protected]>
Subject: Re: [patch] ip autoconfig for PCMCIA NICs
Date: 19 Oct 2001 20:24:42 -0700

Quoted 9 lines · Andrew Morton

This all works fine. However it probably breaks something, but the rather unilluminating comment

#ifdef CONFIG_PCMCIA
        init_pcmcia_ds();               /* Do this last */

#endif

doesn't tell us what.

I'm not sure about the origin of the comment. But I can think of one reason for starting PCMCIA after at least other device drivers have
started: since the kernel generally relies on individual drivers to announce their resource allocations, there is no way to reliably do resource allocation for hot plug devices before non-hot-plug devices have enumerated what resources they're already using.

Quoted 4 lines

Now, every time I try to understand the relationship between socket services, card services, socket drivers and driver services my brain bursts. Could some kind soul please what these things do, and how
they fit together? Thanks.

Card services manages a few things for PCMCIA client drivers: hot plug event handling, resource allocation, PCMCIA bus configuration, Card Information Structure parsing, and some abstractions for talking to memory cards. The Linux version, in the pcmcia_core module, is based heavily on the PCMCIA standard documents. Socket services is the PCMCIA standard API for talking to socket drivers; Linux does not really implement this API and there's a simpler interface between pcmcia_core and socket drivers. The Linux driver services layer, in the "ds" module, supplies a few things for managing device drivers:
stuff for keeping track of which drivers manage which cards, and which logical devices are associated with which cards and drivers. It also provides a user mode pseudo-device for some Card Services functions.

This stuff is also explained in the intro of the Linux PCMCIA Programmer's Guide.

-- Dave
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This information may be relevant to the (long ago) discussion of overhauling in-kernel PCMCIA support and integrating it with the hotplug framework in the 2.5 development cycle.

IIRC, David Woodhouse was considering spearheading this work. Not sure what the current plans might be in this regard.