On Jun 6, 2014, at 12:06 PM, Taylor R Campbell <[email protected]> wrote:
> Date: Fri, 6 Jun 2014 12:56:53 -0500 > From: David Young <[email protected]> > > Here is the proposal that I came up with many months (a few years?) ago > with input from Matt Thomas. I have tried to account for Matt's > requirements, but I'm not sure that I have done so. > > For those ignoramuses among us who remain perplexed by the apparent > difficulty of using a new interrupt delivery mechanism, could you add > some notes to your proposal about what driver authors would need to > know about it and when & how one would use it in a driver? > > Would all architectures with PCI support bus_msi(9), or would PCI > device drivers need to conditionally use it? Why isn't it just a > matter of modifying pci_intr_map, or calling pci_intr_map_msi like in > OpenBSD? Would there be other non-PCI buses with message-signalled > interrupts too? Those that support PCIe or PCIX and support MSIs should change. But we can continue the legacy INT[A-D]. For performance, MSIs should be more efficient. > (Still not having done my homework to study what this MSI business is > all about, I'll note parenthetically that it seems FreeBSD and OpenBSD > have supported MSI for a while, and I understand neither why it was so > easy for them nor what advantage they lack by not having bus_msi(9).)
