* Matthew Wilcox wrote: > On Fri, Jun 19, 2009 at 09:57:48AM +0200, Thierry Reding wrote: > > So the core seems to be able to support multiple functions. On the other > > hand, 8 functions is most likely not enough for our purposes. What kind of > > limitations does PCIe have with more than eight functions? > > > > Otherwise I'm probably stuck with either trying to find some other core that > > can run in bridge mode or having a monolithic driver to serve all logical > > devices. > > OK. The term you're looking for here is ARI (Alternate Routing-ID > Interpretation). This allows a PCIe device to support up to 256 functions > instead of 8. It's defined in PCIe 2.1 and is also available as an ECN > to PCIe 2.0: > > http://www.pcisig.com/specifications/pciexpress/specifications/ECN-alt-rid-interpretation-070604.pdf > > It's not supported by the G33 chipset, but it is supported by the X58 > chipset. To find out if your chipset supports it, run lspci -vvv (as root). > If you see a line along these lines: > > DevCap2: Completion Timeout: Range BCD, TimeoutDis+ ARIFwd+ > > you're in luck (ARIFwd+). If you see a line along these lines: > > DevCap2: Completion Timeout: Not Supported, TimeoutDis- ARIFwd- > > you're not (ARIFwd-). DevCtl2 probably says ARIFwd-, but that's just > because you don't have an ARI-capable device in the slot. > > ARI is a somewhat new feature, so you may well encounter bugs in the > Linux implementation. For example, I just found a bug in the IRQ > swizzling code for ARI devices (and I'll submit a patch for it now). > > I'm very interested in fixing any bugs you find in the ARI code ;-) So this sounds very much like something we could use. It's just that we're pretty much tied to the chipset. The device will use the Poulsbo or its successor. Do you happen to know whether either supports ARI? Thierry -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
