> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Sent: Thursday, November 24, 2022 5:50 AM > > >> This is general PCI MSI logic. So an open related to my rely to patch02, > >> is it correct for PCI core to assume that the real parent imposes all the > >> restrictions and there is no need to further go down the hierarchy? > > > > That was my working assumption and it turned out to be correct with both > > x86 and ARM. > > As a follow up, I went through some of the other architectures, > especially the places which have extra limitations and it turns out that > the restriction comes always from the direct parent. > > If that ever changes then we need a callback which lets us evaluate the > resulting capabilities through the hierarchy. That's nothing which can > be evaluated directly. > > Just look at the x86 hierarchy with IR. IR allows multi PCI-MSI, but the > vector domain does not. Who is right? That's a decision which is made in > the particular hierarchy. make sense. > > For now it's valid that the direct MSI parent has the proper set > available. > probably above can be marked out in the comment.
