Re: [RFC] IDE/ATA/SATA controller hotplug

[Jeff Garzik]

Doug Maxey wrote:
> On Tue, 27 Jul 2004 11:31:15 EDT, Jeff Garzik wrote:
> > >  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.
> >
> > this is already the case in IDE and libata
>
>
> I would have to differ with you here.  From conversations and fairly
> (2 or 3 months ago) experience, the IDE core is not capable of being
> unloaded.

As long as the low-level driver can be unloaded, that's sufficient for 
hardware- and device-hotplug.


> > >  2) extend that support to all child devices; disk, optical,
> > >     and tape.
> >
> > this is already the case in IDE and SCSI
>
>
> Educational question, what would I be looking for when grokking code
> to see this is in place?

Just general refcounting / module support code.


> > >  3) be part of mainline.
> >
> > this is already the case
>
>
> Yes, the drivers are in the mainline.  Just not sure of how many
> platforms will have non-pluggable controllers that need to have them
> hot-plugged. :-)

The PCI API is a hotplug API.  Whether the underlying controller is 
hotpluggable or not is largely irrelevant to low-level drivers.


> > >  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.
> >
> > incorrect
>
>
> Ok, please delineate.  Working off the assumption that 95+% of the
> systems that run Linux are x86 based, and have a single partition for
> the system. In other words, no virtual processors, where each is
> totally separate from the other.

That's completely irrelevant.  libata and the IDE core work without 
change on x86 and non-x86 systems.


> > >  - Where should this capability go?  Fork a subset of IDE
> > >    controllers, and put them under the arch specific dir?
> > >    Or include all devices?
> >
> > there is nothing arch-specific about this
>
>
> Again, going back to my original premise, that is, which platforms do
> you foresee needing this capability?  I know that all should have
> eventually.

All platforms should be considered hotplug.

	Jeff


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