On Sat, Jan 09, 2021 at 07:31:46PM +0100, Michael Walle wrote: > Hi Bjorn, > > Am 2021-01-08 22:20, schrieb Bjorn Helgaas: > > On Wed, Dec 30, 2020 at 07:53:17PM +0100, Michael Walle wrote: > > > The Intel i210 doesn't work if the Expansion ROM BAR overlaps with > > > another BAR. Networking won't work at all and once a packet is sent > > > the > > > netdev watchdog will bite: > > > > 1) Is this a regression? It sounds like you don't know for sure > > because earlier kernels don't support your platform. > > Whats the background of the question? The board is offially supported > since 5.8. I doubt that the code responsible to not touch the ExpROM > BAR in pci_std_update_resource() were recently changed/added; the > comment refers to a mail from 2005. So no I don't think it is a > regression per se. Just asking because it affects the urgency. If we added a regression during the v5.11 merge window, we'd try hard to fix it before v5.11-final. But it sounds like the problem has been there a long time, so a fix could wait until v5.12. > It is just that some combination of hardware and firmware will program > the BARs in away so that this bug is triggered. And chances of this > happing are very unlikely. > > Do we agree that it should be irrelevant how the firmware programs and > enables the BARs in this case? I.e. you could "fix" u-boot to match the > way linux will assign addresses to the BARs. But that would just work > around the real issue here. IMO. I agree, Linux should work correctly regardless of how firmware programmed the BARs. > > 2) Can you open a bugzilla at https://bugzilla.kernel.org and attach > > the complete dmesg and "sudo lspci -vv" output? I want to see whether > > Linux is assigning something incorrectly or this is a consequence of > > some firmware initialization. > > Sure, but you wouldn't even see the error with "lspci -vv" because > lspci will just show the mapping linux assigned to it. But not whats > written to the actual BAR for the PCI card. I'll also include a > "lspci -xx". I've enabled CONFIG_PCI_DEBUG, too. > > https://bugzilla.kernel.org/show_bug.cgi?id=211105 > > > 3) If the Intel i210 is defective in how it handles an Expansion ROM > > that overlaps another BAR, a quirk might be the right fix. But my > > guess is the device is working correctly per spec and there's > > something wrong in how firmware/Linux is assigning things. That would > > mean we need a more generic fix that's not a quirk and not tied to the > > Intel i210. > > Agreed, but as you already stated (and I've also found that in the PCI > spec) the Expansion ROM address decoder can be shared by the other BARs > and it shouldn't matter as long as the ExpROM BAR is disabled, which is > the case here. My point is just that if this could theoretically affect devices other than the i210, the fix should not be an i210-specific quirk. I'll assume this is a general problem and wait for a generic PCI core solution unless it's i210-specific. Bjorn
