Description of problem: I have a platform with Opteron/HT2100/HT1000 with an Intel 82571 PCIe ethernet controller. Both the original Fedora 9 kernel and the update today (2.6.25.3-18) don't enable MSI for the Intel ethernet module. If I use vanilla 2.6.25.3, it *does* use MSI. I would like to use MSI on this platform to allow flexibility with sharing IRQs. How reproducible: Always. Steps to Reproduce: 1. Boot F9 on a platform with an 82571 ethernet device. 2. look at /proc/interrupts Actual results: ethX uses IO-APIC-fasteoi. Expected results: ethX uses PCI-MSI-edge. Additional info: I have attached dmesg and /proc/interrupts from the two kernels. I don't see anything in dmesg that explains why MSI is not in use. Nothing should be blacklisted, ethernet works fine in MSI mode on the vanilla kernel.
Created attachment 305540 [details] dmesg of fc9
Created attachment 305541 [details] dmesg of vanilla
Created attachment 305542 [details] /proc/interrupts of fc9
Created attachment 305543 [details] /proc/interrupts of vanilla
boot with pci=msi By default, we can't enable it, because the MSI support causes a lot of systems to not even boot.