Messages in this thread | | | Subject | Re: [RFC] IDE/ATA/SATA controller hotplug | Date | Tue, 27 Jul 2004 15:18:44 -0500 | From | Doug Maxey <> |
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On Tue, 27 Jul 2004 11:31:15 EDT, Jeff Garzik wrote: >Doug Maxey wrote: >> Howdy! >> >> 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 >> motherboard. >> >> 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. > >Why do you think libata is not already hotplug capable, WRT controllers?
Notice that I did qualify with "possibly". Am not 100% up to speed on the libata, although it did appear clean, and I am attempting to get to total understanding. My perception at this time is that the PATA controllers is where the bulk of the work would be needed. If that is not true, then great, the kernel is much further along.
Do you have any test cases that are normally run? Assuming that if these did it exist, they would be more manually than ant kind of automated.
> > >> 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.
> > >> 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?
> > >> 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 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.
> > >> - Assuming the capability is added, what rework would be acceptable >> for block devices? > >none
None, in the sense that notification is already present, and no new mechanism is required, or none in the sense that if a hotplug event occurs, no one cares?
> > >> - 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.
> > >> - should we work to the goal of having the capability for all >> platforms, and all IDE devices? > >of course > > Jeff > >
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