On Tue, Dec 13, 2005 at 08:50:13AM -0600, James Bottomley wrote: > On Tue, 2005-12-13 at 07:22 -0600, Michael Reed wrote: > > I believe the biggest issue with VISWS is that it appears to need > > mmiowb() and we likely don't know how to implement it. Hence, for > > that platform, it would make sense to replace the mmiowb() with a > > posting read. > > Well, there's an easy way to tell ... the reason for the mmiowb in the > qla1280 driver is supposed to be an SMP race, according to the > description, so if it fails on UP as well there's something else going > on here ... The 320 was available with two CPUs, and though the post doesn't say what this particular one had, it likely had two. The original post also indicated a problem with a two-cpu motherboard, though I don't think that was the 320 (VisWS). > I'm still suspicious because the mmiowb() in this driver replaced a > posted write flush instruction, which altered the behaviour of the > driver. The qla1280 is just rare enough that it might have taken this > long to notice ... The 12160 is in most Altix machines and behaves just like a 1280. If there were a problem with it in this context, we'd know about it. I'm still betting on the old problem (time moves downward): cpu A lock posted pio write X unlock cpu B lock posted pio write Y unlock PCI bus retire pio write Y retire pio write X The Qlogic architecture doesn't like this. jeremy - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
