On Mon, May 07, 2012 at 09:44:16AM -0700, Bjorn Helgaas wrote: > On Mon, May 7, 2012 at 12:35 AM, Andreas Herrmann > <andreas.herrmann3@xxxxxxx> wrote: > > On Fri, May 04, 2012 at 10:35:05AM -0600, Bjorn Helgaas wrote: > >> On Fri, May 4, 2012 at 7:03 AM, Andreas Herrmann > >> <andreas.herrmann3@xxxxxxx> wrote: > >> > On Wed, May 02, 2012 at 11:33:17AM -0600, Bjorn Helgaas wrote: > >> >> On Fri, Apr 27, 2012 at 8:36 AM, Andreas Herrmann > >> >> <andreas.herrmann3@xxxxxxx> wrote: > >> >> > > >> >> > Once upon a time this function was overloaded with quirky stuff to fix > >> >> > resource detection on systems w/ _CRS defects (seems that some Sun and > >> >> > HP systems were affected). > >> >> > > >> >> > See commit 30a18d6c3f1e774de656ebd8ff219d53e2ba4029 > >> >> > (x86: multi pci root bus with different io resource range, on 64-bit) > >> >> > > >> >> > Restore the old function and thus decouple it from the quirk that is > >> >> > CPU family specific (e.g. it won't work on AMD family 15h CPUs). BTW, > >> >> > I assume that the _CRS stuff is working on current systems. > >> >> > > >> >> > This is required to properly initilize the numa_node information of > >> >> > existing PCI busses and associated devices. > >> >> > >> >> I applied some of Yinghai's patches that also touch this area. Can > >> >> you refresh these so they apply on top of my "next" branch > >> >> (git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git next)? > >> > > >> > Arrgh, will adapt my patch and resend it (asap). > >> > > >> >> Can you also be more specific about what these patches fix? > >> > > >> >> My understanding is that amd_bus.c (1) sets NUMA info with > >> >> set_mp_bus_to_node() and (2) figures out MMIO and I/O port apertures, > >> >> which are only used when blind probing and when ignoring _CRS. > >> >> > >> >> It seems like the main change in this patch is that we skip (2) > >> >> completely when family >= 0x11, and I don't understand what that could > >> >> fix. > >> > > >> > The patch restores a very old function that was used to detect the > >> > nearest node for a PCI bus, so yes it's used to do (1). IMHO this > >> > function was totally screwed up with Yinghai's code to do (2). It > >> > seems that Sun has (had?) some systems where (2) was req'd. I don't > >> > care about this part. But I'd like to do (1) on all AMD CPU NUMA > >> > systems. > >> > >> Thanks for the explanation. But I'm afraid I'm still confused. > >> > >> First, it sounds like you're trying to change the way we do part (1), > >> i.e., the set_mp_bus_to_node() calls, but I think the effect of your > >> patch is to stop doing part (2) in some cases. > >> > >> Second, I am pretty sure that the current early_fill_mp_bus_info() > >> (before your patch) does the exact same set_mp_bus_to_node() calls as > >> your early_fill_mp_bus_to_node() does. > > > > > > I want to do (1) on all AMD CPUs that might be used in NUMA systems. > > > > What's done for (2) is very specific to certain AMD CPU families -- > > some of the register accesses are wrong/incomplete for newer AMD > > CPUs. Furhtermore _CRS should provide the required info. I really > > don't want to extend all the quirky stuff in (2) for future AMD CPUs. > > I'm all in favor of limiting part (2) to older AMD CPUs. I certainly > don't want to maintain it for future CPUs. > > >> Finally, on all systems with ACPI, the set_mp_bus_to_node() call in > >> pci_acpi_scan_root() should be doing what you need. In fact, that > >> call happens later, so it should be overwriting the information filled > >> in by amd_bus.c. If there's something wrong in this ACPI path, the > >> most likely cause is a BIOS defect, such as a missing _PXM method on > >> the PNP0A03/0A08 host bridge device. > > > > Good point. I'll check what's wrong in this ACPI path. > > I hope you find something, especially if it's a bug in the Linux code > that interprets the NUMA info. Then we could fix that and limit both > parts to older CPUs. Simply, there is no _PXM object for the host bridge devices. At least on the systems that I checked. I'll try to find out whether this is sort of "common BIOS practice" on AMD boxes and how to avoid that in the future. However it seems that a fix in Linux is appropriate for existing systems. Andreas -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
