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Lukasz Kosewski provided an update on his efforts to create a hotswap infrastructure for libATA, allowing the driver to properly handle hotplug interrupts. He notes that along with the generic infrastructure he plans to include, "a specific implementation of this infrastructure in the Promise SATA150 and SATAII150 line of controllers." He began working on this in late July, noting that at this time drivers for the formentioned hard drives "mostly work", and he has continued to clean up the infrastructure based on suggestions from libATA author Jeff Garzik [story]. Lukasz went on to note, "once the infrastructure is accepted, anyone with a hotswap-unsupported controller and some time on their hands will easily be able to integrate hotswap in; that is the whole goal of an infrastructure." He added that alternatively if provided with a controller and documentation, "I will add the support and test the b'jesus out of it".
Jeff Garzik commented, "once the infrastructure is there, I'll probably add support for several controllers myself." He went on to explain that some controllers don't have an explicit hotplug interrupt, but can still support hotswapping. Alan Cox [interview] was concerned about Parallel ATA (IDE) support, "for PATA we may need to reprogram both drives so please be sure that is allowed for. Also much PATA is 'warm swap' not 'hot swap' as we have to perform actions in software prior to the swap."
From: Ravi Wijayaratne [email blocked] To: lkosewsk, [email blocked] Subject: Hotswap support for libata Date: Fri, 2 Sep 2005 15:44:18 -0700 (PDT) Hi Luke I was wandering whether you could direct me to a place where I could find the most up to date patches for libata hotplug support you authored. Has Jeff Garzik decided to integrate this code to 2.6 libata ? Thanks Ravi ------------------------------ Ravi Wijayaratne
From: Lukasz Kosewski [email blocked] Subject: Re: Hotswap support for libata Date: Fri, 2 Sep 2005 23:23:41 -0700 On 9/2/05, Ravi Wijayaratne [email blocked] wrote: > I was wandering whether you could direct me to > a place where I could find the most up to date > patches for libata hotplug support you authored. > > Has Jeff Garzik decided to integrate this code > to 2.6 libata ? Hey Ravi, You are on the money in one way; it's September, and I promised everyone I'd work on it come September. However, this is a loose timeline; specifically, I'll be available to work on them come the 6th of this month. So expect some more activity then :) First of all let me clarify something though; these patches are two parts: - a libata hotswap infrastructure that allows a driver which understands and properly handles hotplug interrupts to hotswap drives. - a specific implementation of this infrastructure in the Promise SATA150 and SATAII150 line of controllers. I've been getting quite a few emails offline from people excited with being able to arbitrarily hotswap all Serial ATA drives, and I should point out that unless people with the other controllers types (ie. nForce controllers, Sil controllers, etc.) actually add support for capturing hotswap interrupts and use the hotswap infrastructure, they will still not support hotplug. If you send me a controller and the docs for it, I will add the support and test the b'jesus out of it, but otherwise only the Promise controllers will have this support. Here's the current status for all to see: - I submitted initial patches near the end of July, which were heavily tested on UP machines and Promise SATA150/SATAII150 Tx4/Tx2 Plus controllers. They mostly work. - Jeff suggested some improvements that would make them work better, and these improvements work better for a general infrastructure (as opposed to a sata_promise-centric one). - I sent in patches implementing the improvements on the 1st of August. They weren't tested at all because I didn't have access to the hardware at that time, but I wanted some feedback. Those patches DO NOT WORK, however, they are very close to what I want (I need to add a workqueue and streamline error-handling a bit more). - Come the 6th, I'm going to a location where I'll have access to the controller, as well as UP boxes and an SMP box. So you can expect new patches, say, by the 10th or 11th that should be well tested and robust on UP and SMP machines for Jeff's perusal. So, if you really want hotswap now now now, you'll have to download my patches and fiddle with them. They're available in the kernel mailing list archives, if you search for 'hotswap libata', they will come up. Otherwise, I ask you to be patient for another wek or so and the good stuff will fall from the sky. Cheers, Luke Kosewski
From: Lukasz Kosewski [email blocked] Subject: Re: Hotswap support for libata Date: Fri, 2 Sep 2005 23:25:53 -0700 On a happier note, once the infrastructure is accepted, anyone with a hotswap-unsupported controller and some time on their hands will easily be able to integrate hotswap in; that is the whole goal of an infrastructure. So if your controller isn't supported, but you know something about it (or better yet, you yourself have docs), adding hotswap support to it should be too hard. Luke Kosewski
From: Jeff Garzik [email blocked] Subject: Re: Hotswap support for libata Date: Sat, 03 Sep 2005 02:38:00 -0400 Lukasz Kosewski wrote: > On a happier note, once the infrastructure is accepted, anyone with a > hotswap-unsupported controller and some time on their hands will > easily be able to integrate hotswap in; that is the whole goal of an > infrastructure. So if your controller isn't supported, but you know > something about it (or better yet, you yourself have docs), adding > hotswap support to it should be too hard. Once the infrastructure is there, I'll probably add support for several controllers myself. Many controllers don't have an explicit hotplug interrupt, but rather we must examine the PhyRdy bit in the standard SError register for details. If the bit's state changes in any way (including two or more state changes), we (a) check for device presence, and (b) if device is present, initialize it (SET FEATURES - XFER MODE, etc.). Jeff
From: Alan Cox [email blocked] Subject: Re: Hotswap support for libata Date: Sat, 03 Sep 2005 18:53:11 +0100 On Sad, 2005-09-03 at 02:38 -0400, Jeff Garzik wrote: > controllers myself. Many controllers don't have an explicit hotplug > interrupt, but rather we must examine the PhyRdy bit in the standard > SError register for details. If the bit's state changes in any way > (including two or more state changes), we (a) check for device presence, > and (b) if device is present, initialize it (SET FEATURES - XFER MODE, > etc.). For PATA we may need to reprogram both drives so please be sure that is allowed for. Also much PATA is "warm swap" not "hot swap" as we have to perform actions in software prior to the swap. Alan
