On Wed, Apr 01, 2009 at 04:23:10PM -0600, Alex Chiang wrote: > * Sam Ravnborg <sam@xxxxxxxxxxxx>: > > On Wed, Apr 01, 2009 at 12:37:49PM -0600, Alex Chiang wrote: > > > * Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>: > > > > On Wed, 1 Apr 2009 10:01:12 -0700 (PDT) > > > > Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > > On Tue, 31 Mar 2009, Jesse Barnes wrote: > > > > > > > > > > > > Please consider pulling my PCI tree from > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 > > > > > > linux-next > > > > > > > > > > This produces > > > > > > > > > > WARNING: drivers/built-in.o(.text+0x69a1): Section mismatch in > > > > > reference from the function dev_rescan_store() to the > > > > > function .devinit.text:pci_rescan_bus() The function > > > > > dev_rescan_store() references the function __devinit > > > > > pci_rescan_bus(). This is often because dev_rescan_store lacks a > > > > > __devinit annotation or the annotation of pci_rescan_bus is wrong. > > > > > > > > > > Hmm? > > > > > > > > Arg how did I miss that? Maybe the last build I did was missing > > > > hotplug support or something... Anyway looking now (at first glance I > > > > think pci_rescan_bus needs to drop __devinit). > > > > > > This was my fault. pci_rescan_bus() definitely does not want > > > __devinit. > > > > > > But I'm confused -- didn't we used to have an option in > > > menuconfig under Kernel Hacking that would turn on section > > > mismatch warnings? I used to have that turned on, and don't > > > remember turning it off, and I can't find it now. > > > > > > I'm told that we're supposed to set it on the make command line, > > > like: > > > > > > make CONFIG_DEBUG_SECTION_MISMATCH=y -j16 > > > > > > or something. Has this changed recently or am I just imagining > > > things (or just plain stupid?) > > > > That was maybe one year ago we had it in menuconfig. > > When I get on top of things I will enable it and try to > > help fixing the remaining warnings. > > Ah, ok. > > > I have resisted enabling it for now as I cannot support the people > > that see the warnings atm. > > Nod, makes sense. > > I took a look at the warning that Linus mentioned, and I'm not > entirely sure how to fix it. The problem is this: > > http://git.kernel.org/?p=linux/kernel/git/jbarnes/pci-2.6.git;a=commit;h=3ed4fd96b3188406ac5357d9290bcffa08c65cf6 > > I initially annoted pci_rescan_bus as __devinit, which it > shouldn't have. Removing the annotation though, produces these > other warnings: > > WARNING: vmlinux.o(.text+0x1b9be6): Section mismatch in reference from the function pci_rescan_bus() to the function .devinit.text:pci_scan_child_bus() > The function pci_rescan_bus() references > the function __devinit pci_scan_child_bus(). > This is often because pci_rescan_bus lacks a __devinit > annotation or the annotation of pci_scan_child_bus is wrong. > > Reading through Documentation/PCI/pci.txt says that under > CONFIG_HOTPLUG, __devinit should be a nop? The documentation is not up-to-date in this respect. Annotating a function __devinit will no matter the configuration locate the code in a section named .devinit.text We then postprocess this section for illegal references using modpost. The PCI_HOTPLUG code has often been troublesome with respect to these checks as this code is only relevant if CONFIG_HOTPLUG is enabled and will often not even be included in the kernel if not enabled. This is true for pci_rescan_bus() for example. And we would like to export these symbols too. But we do not allow exported symbols to be annotated __devinit as this code will be blown away in some configurations. So the correct solution which you also used in your patch is to tell modpost to ignore references to *init sections from this specific funtion as they are OK. Sam -- 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
