On Thu, 3 Jun 2004, Pete Zaitcev wrote: > It is definitely needed for 2.4 in Red Hat, however I tried to turn > it down for generic code even though it's not my area and Matt and Alan > didn't have a problem with it. The problem comes about because > Red Hat installer tries to optimize things and probes something > in parallel, so when it runs updfstab it can overlap with normal > accesses and devices choke. I assumed that SuSE was not affected, > but apparently they were, or why else Vojtech became involved. > > I raised the question of applicability to 2.6 and the concensus was > that control queueing in uhci-hcd takes care of it. Now it seems that > it doesn't, is this accurate? Vojtech, did you actually see the > failure on 2.6, or it's just speculation by Gary & Santosh @Dell?
There were two different issues involved here: lack of queuing for control requests, and control requests interfering with ongoing SCSI commands. The queuing part matters only for 2.4. The interference part matters for all versions of Linux; it depends only on whether the device is able to walk and chew gum at the same time. Probably most devices can, though I'm sure Matt knows some examples of devices that can't. The idea of using a different semaphore rather than dev->serialize is still workable for 2.6. The question is, should we do it? Or is the affected population sufficiently small that we don't care? Note: There have been reports posted from users of other devices (scanners) that were similarly confused by multiple control requests arriving while they were trying to get some real work done. Alan Stern ------------------------------------------------------- This SF.Net email is sponsored by the new InstallShield X. >From Windows to Linux, servers to mobile, InstallShield X is the one installation-authoring solution that does it all. Learn more and evaluate today! http://www.installshield.com/Dev2Dev/0504 _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
