I am booting a kernel with CONFIG_ACPI=n on a platform which does not support ACPI. -Brian On Fri, Jul 4, 2014 at 1:59 AM, Yijing Wang <wangyijing@xxxxxxxxxx> wrote: >>>> There is a NVIDIA G96 GPU (which is PCIe only) hanging off of a PCIe >>>> <-> PCI bridge (all on one card), which is plugged into a motherboard >>>> with the 430FX chipset (PCI 2.0 supported). >>>> >>>> The GPU PCI device, of course, has full support for MSI. However my >>>> understanding is that MSI won't actually work here. This is confirmed >>>> by the fact that if we let nouveau enable MSI, the device doesn't work >>>> (presumably due to lack of interrupt delivery, although I admit to not >>>> having debugged it that far). How do I, as a nouveau driver developer, >>>> know not to call pci_enable_msi? Or alternatively how can >>>> pci_enable_msi be taught not to succeed in this case? >>> >>> You can set bus_flags or global pci_msi_enable flag by add quirk function. >>> You can refer to examples in drivers/pci/quirk.c >>> >>> Linux support some broken chipsets or devices to disable msi during device initialization by add quirk. >> >> So let me get this straight -- you're suggesting I add a quirk for >> every PCI chipset that doesn't support MSI? There are probably >> hundreds of these... anything made before 1999 or so, and probably a >> bunch since then too. There _has_ to be a way to do this generically. >> Is the PCI spec version anywhere in the root hub? > > There is no register to identify PCI spec version in PCI config space registers. > If your platform boot up with ACPI, you can setting ACPI FADT boot flag to disable MSI, > you can refer to this in ACPI 5.2.9.3 chapter "Fixed ACPI Description Table Boot Architecture Flags" > > >> >> Perhaps we can check if every bridge on the way to the CPU has the MSI >> capability (including the root hub)? (And naturally _that_ won't >> work... on my sandybridge laptop, the host bridge doesn't have the MSI >> cap but the system most definitely supports MSI.) >> >> Adding Bjorn... perhaps you know? Some of the info has been stripped >> out by now, you can see the full lspci -vvvxxx at >> http://marc.info/?l=linux-pci&m=140443441730503&w=2 >> >> -ilia >> >> . >> > > > -- > Thanks! > Yijing > -- 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
