From: Matthew Wilcox <[EMAIL PROTECTED]> Date: Thu, 6 Sep 2007 05:57:31 -0600
> I'm not sure your analysis is correct. Here's what my draft copy of > the pcie 2.0 spec says: > > Enble No Snoop If this bit is Set, the Function is permitted to > Set the No Snoop bit in the Requester Attributes of transactions it > initiates that do not require hardware enforced cache coherency (see > Section 2.2.6.5). Note that setting this bit to 1b should not cause > a Function to Set the No Snoop attribute on all transactions that it > initiates. Even when this bit is Set, a Function is only permitted > to Set the No Snoop attribute on a transaction when it can guarantee > that the address of the transaction is not stored in any cache in > the system. This bit permitted to be hardwired to 0b if a Function > would never Set the No Snoop attribute in transactions it initiates. > Default value of this bit is 1b. > > That implies that devices are only allowed to set it when it's safe to > do so ... and we don't need to turn it off. This is my understanding of this area of PCI-E as well, and I also agree that therefore we should not turn this bit off. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
