On Sat, Feb 22, 2020 at 8:55 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > On Mon, Apr 16, 2018 at 07:33:57AM -0700, Matt Turner wrote: > > Commit f75b99d5a77d63f20e07bd276d5a427808ac8ef6 (PCI: Enforce bus > > address limits in resource allocation) broke Alpha systems using > > CONFIG_ALPHA_NAUTILUS. Alpha is 64-bit, but Nautilus systems use a > > 32-bit AMD 751/761 chipset. arch/alpha/kernel/sys_nautilus.c maps PCI > > into the upper addresses just below 4GB. > > > > I can get a working kernel by ifdef'ing out the code in > > drivers/pci/bus.c:pci_bus_alloc_resource. We can't tie > > PCI_BUS_ADDR_T_64BIT to ALPHA_NAUTILUS without breaking generic > > kernels. > > > > How can we get Nautilus working again? > > I don't see a resolution in this thread, so I assume this is still > broken? Anybody have any more ideas? Indeed, still broken. I can add Kconfig logic to unselect ARCH_DMA_ADDR_T_64BIT if ALPHA_NAUTILUS, but then generic kernels won't work on Nautilus. It doesn't look like we have any way of opting out of ARCH_DMA_ADDR_T_64BIT at runtime, and doing enough plumbing to make that work is not worth it for such niche hardware. Maybe removing Nautilus from the generic kernel build is what I should do until such a time that we really fix this? Or maybe I could put a hack in pci.c that more or less undoes d56dbf5bab8c on Nautilus. #if defined CONFIG_ARCH_DMA_ADDR_T_64BIT && !defined SYS_NAUTILUS. Or maybe I just need to take a weekend and try to understand the PCI code, instead of applying patches I don't understand and praying :) Thoughts? Other suggestions?
