[RFC] IDE/ATA/SATA controller hotplug

From: Doug Maxey
Date: Mon Jul 19 2004 - 14:48:51 EST


This note went out originally to a semi-internal list, but after
several comments, posting it here...

As we chug along here in PPC64 land, we (meaning IBM internal) have
been given a requirement to make all devices on our new DLPAR
(POWER5 and later) systems be hotplug capable. This includes ALL
PCI devices on the system, even those that are soldered on the

This raises some interesting issues when dealing with IDE devices.

I realize there is considerable work under way (hi Bart :) to clean
up the 2.6 trees. This hotplug work would be another delta on top
of that work.

The changes could also possibly affect the libata work, as that
could also be touched by work on the attached devices themselves.

What I would like is input on the general strategy that should be
taken to modify the controller/adapter and device stack to:

1) be first class modules, where all controllers/adapters are
capable of being loaded and unloaded. This is directed mostly at
IDE/Southbridge controller/adapter devices.

2) extend that support to all child devices; disk, optical,
and tape.

3) be part of mainline.

The items I perceive at the top of the issue list are:

- The primary platforms for IDE/ATA devices are x86 based, and
certainly do not care about having this capability.

- Assuming the capability is added, what rework would be acceptable
for block devices?

- Where should this capability go? Fork a subset of IDE
controllers, and put them under the arch specific dir?
Or include all devices?

- should we work to the goal of having the capability for all
platforms, and all IDE devices?


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