On Thursday 21 February 2013 03:04 PM, James Hogan wrote: > Hi Vineet, > > On 21/02/13 09:08, Vineet Gupta wrote: >> On Wednesday 20 February 2013 08:22 PM, James Hogan wrote: >>> Make a copy of the device tree blob in non-init memory. It is required >>> when using built-in device tree files that the platform code copies the >>> blob to non-init memory prior to calling unflatten_device_tree(), >>> otherwise the strings that the device tree refer to will get poisoned >>> and potentially reused, breaking later reading of the device tree >>> post-init (such as compatible matching in modules, debugfs, and the >>> procfs interface). >> While the patch conceptually looks correct, I'm not sure why any user of DT - >> post-init would refer to DT bindings using of_fdt_* API which use the flat >> tree, >> instead of the binary tree (more efficient in space/usage). Is this to >> support >> some in-transition drivers and other code. > The strings aren't copied when the devicetree is unflattened, so the > unflattened version still points into initdata, so all the strings "in" > the unflattened version are wiped when it's freed too.
You are absolutely right, so ARC port is infested with same ticking time bomb ! Thanks for the heads up - I'll queue up a fix - but that will go in after the first pull request as I want any change, however minimal/local to cook in -next for some time (for paranoid sake at this stage) > Documentation/kbuild/makefiles.txt has this to say: >> dtc >> Create flattend device tree blob object suitable for linking >> into vmlinux. Device tree blobs linked into vmlinux are placed >> in an init section in the image. Platform code *must* copy the >> blob to non-init memory prior to calling unflatten_device_tree(). > Other architectures using the builtin dtb also do the copy. I presume > it's in initdata in the first place to avoid keeping the built-in one > around if one is provided by the bootloader instead. Makes sense ! -Vineet -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
