On Tue, May 18, 2010 at 20:14, Tejun Heo <tj@xxxxxxxxxx> wrote: > On 05/18/2010 07:53 PM, Kay Sievers wrote: >> Tejun, >> an AN capable SATA optical drive seems to send AN events with every >> open(). For userspace these look the same as the media changed events, >> and cause a loop when udev checks if there is a new media. Any ideas >> if these AN events are expected, or useful for anything? > > The open() path issues several commands and it could be that the drive > is raising AN when certain conditions are met just in case. After all > windows only uses single command for media presence polling, so > there's nothing stopping vendors from using TUR, for example, as the > level triggered check point to see whether media is available and > raise AN if so. After all, that wouldn't lose any event and in case > the internal state went out of sync, it would work as an easy resync > point. > > Long term, I think the only solution is to do what windows does for > media presence polling; otherwise, we'll keep running into various > obscure issues. For short term, I dunno. Don't use AN for the time > being? :-) Yeah, the problem is that we already have the problem with current software that causes the event loop. And we need a solution now. :) We might need to switch the AN stuff off by default in the kernel, and only enable it when we know we are able to handle it? Kay -- To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
