Re: IDE Hotswap

[Bartlomiej Zolnierkiewicz <bzolnier@elka.pw.edu.pl>]

On Tuesday 28 September 2004 23:45, Alan Cox wrote:
> On Maw, 2004-09-28 at 22:38, Bartlomiej Zolnierkiewicz wrote:
> > No and such workaround won't work anyway because
> > re-register operation is nothing else but unregister+register.
> 
> If you grab the 2.6.8.1-ac patch you can do IDE controller hotplugging
> and a few other things but not yet drive hotplugging. 2.4 can do drive
> hotplug although you need a small -ac patch if you see wrong disk
> geometry data.
> 
> For new controllers (ie SATA ones) use Jeff Garzik's serial ATA layer as
> that is a lot cleaner and the SCSI layer already has a good basic
> understanding of hotplug management.
> 
> > Any help/support is appreciated.
> 
> Except for the dynamic stuff I consider the problem solved. Its up to
> you when and what you merge and I understand why you want to get stuff
> like sysfs there. 

Your patch is a nice start but it don't solve main issues, not to even
mention minor stuff like leaving /proc/ide/<chipset> around.

Merging it now is asking for problems.

> For drive level hotplug its actually a lot easier and I guess that is
> the case most users care about. The changes done for 2.6 clean up stuff

drive level hotplug is actually much harder
and it is _required_ for controller level hotplug, no? :)

> like suspend mean the nasties in 2.4 for sequencing have gone away. No
> refcounting needed since the block and fs layer are doing it all for

It helps but you still get bunch of races.  Refcounting is _really_ needed.

> you. TTY layer, revoke(), and some other current critical bonfires first
> before I can help with that however.

Fine.

Bartlomiej