On Tue, Feb 19, 2019 at 06:19:30PM -0500, Paolo Bonzini wrote: > > > > Makes sense, but it is also abstraction time. :) What if instead there > > > was a function > > > > > > void msi_allocate_irqs(PCIDevice *pdev, int num, bool fallback_to_intx); > > > > > > and then ich.c did > > > > > > irqs = msi_allocate_irqs(pdev, 1, true); > > > s->irq = irqs[0]; > > > g_free(irqs); > > > > > > ? "if msi_enabled raise MSI else raise INTX" is really a common idiom. > > > > > > Thanks, > > > > > > Paolo > > > > Maybe it is but the specific issue is not about fallback to INTX of PCI > > (is the fallback broken for ahci? I don't know). > > It works, the above is just a new abstraction. > > > The trick is there's no pdev at all. > > The trick :) is that in ich.c there is a pdev. Right now we are assigning to > s->irq either the INTX irq (if PCI) or a sysbus irq (if sysbus), but then > we need to know about MSI with a wrapper around s->irq.
Oh you mean just for PCI. > Instead, my suggestion is to put the wrapper in the PCI core as a qemu_irq > callback---or perhaps in ich.c, but anyway ahci.c should not care that there > could be a PCI AHCI device and it would have two different interrupt modes. I like it very much that devices call pci_set_irq, I'd rather not have callbacks. I think the wrapper thay calls either pci_set_irq isn't a problem, problem is MSI/X has multiple vectors, INTX doesn't. So for many devices there's something extra that happens just in one mode but not the other to deal with multiple vectors. So I don't think it can be an abstraction that everyone uses. But yes it can be a helper function. In fact mptsas_update_interrupt seems not to be PCI spec compliant: it sets both MSI and INTX. CC original contributor with this question. > In fact, doing this would also remove the need for s->container, I think. > > Paolo