On Thu, Jun 06, 2024 at 01:57:56PM +0100, Jonathan Cameron wrote: > Or are you thinking we can make something like the following work > (even when we can't do dynamic msix)? > > Core bring up facilities and interrupt etc. That includes bus master > so msi/msix can be issued (which makes me nervous - putting aside other > concerns as IIRC there are drivers where you have to be careful to > tweak registers to ensure you don't get a storm of traffic when you > hit bus master enable. > > Specific driver may bind later - everything keeps running until > the specific driver calls pci_alloc_irq_vectors(), then we have to disable all > interrupts for core managed services, change the number of vectors and > then move them to wherever they end up before starting them again. > We have to do the similar in the unwind path. My recollection is that Thomas Gleixner has brought up dynamic MSI-X allocation. So if both the PCI core services as well as the driver use MSI-X, there's no problem. For MSI, one approach might be to reserve a certain number of vectors in the core for later use by the driver. Thanks, Lukas
