On 02/28/18 12:26, Rob Herring wrote: > Sorry for the delay, been away for a few days. > > On Mon, Feb 19, 2018 at 12:24 AM, Frank Rowand <frowand.list@xxxxxxxxx> wrote: >> >> On 02/18/18 17:46, Rob Herring wrote: >>> On Sun, Feb 18, 2018 at 6:29 PM, <frowand.list@xxxxxxxxx> wrote: >>>> From: Frank Rowand <frank.rowand@xxxxxxxx> >>>> >>>> kbuild test robot reported a new warning for a recent patch: >>>>>> drivers/of/overlay.c:832:2: error: implicit declaration of function 'of_fdt_unflatten_tree' [-Werror=implicit-function-declaration] >>>> of_fdt_unflatten_tree(new_fdt, NULL, &overlay_root); >>>> >>>> The cause is that the prototype for of_fdt_unflatten_tree() in >>>> include/linux/of_fdt.c is guarded by OF_EARLY_FLATTREE. > > Umm, this is not true. of_fdt_unflatten_tree is outside the ifdef for > OF_EARLY_FLATTREE. Brown paper bag. :-( As you note below, CONFIG_OF_FLATTREE is the relevant option. >>>> >>>> This was a pre-existing problem for any overlay related caller of >>>> of_fdt_unflatten_device_tree(), who was then going to pass the >>>> unflattened tree to of_overlay_apply(). After the patch that triggered >>>> this warning, all other overlay callers of of_fdt_unflatten_device_tree() >>>> no longer exist, so adding the select to OF_OVERLAY is a sufficient fix. >>>> >>>> To reproduce the warning: >>>> Use the .config attached to https://lkml.org/lkml/2018/2/17/268 >>>> make ARCH=i386 olddefconfig >>>> make ARCH=i386 CC=gcc-7 drivers/of/overlay.o >>>> >>>> Signed-off-by: Frank Rowand <frank.rowand@xxxxxxxx> >>>> --- >>>> drivers/of/Kconfig | 1 + >>>> 1 file changed, 1 insertion(+) >>>> >>>> diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig >>>> index 783e0870bd22..00a6abfaaec7 100644 >>>> --- a/drivers/of/Kconfig >>>> +++ b/drivers/of/Kconfig >>>> @@ -92,6 +92,7 @@ config OF_RESOLVE >>>> config OF_OVERLAY >>>> bool "Device Tree overlays" >>>> select OF_DYNAMIC >>>> + select OF_EARLY_FLATTREE > > This should really have been OF_FLATTREE... Yes. This only fixed the warning because OF_EARLY_FLATTREE selects OF_FLATTREE. >>> If we do this, we might as well kill OF_EARLY_FLATTREE. What platform >>> really boots from not FDT, but uses DT without overlays? >> >> Making sure I'm understanding... So you want to remove OF_EARLY_FLATTREE >> and convert the current users of it to OF_FLATTREE? > > Right. OF_EARLY_FLATTREE just controls everything that's in __init > section anyway. So the question is it worth a kconfig option to > control code that's in the __init section and will get discarded > anyway? > > >> I don't see any way to directly configure OF_FLATTREE and I don't see anyk >> Kconfig file selecting it, other than drivers/of/Kconfig which selects >> OF_FLATTREE from OF_EARLY_FLATTREE. So as far as I can tell, the two >> config options are essentially a single config option. Meaning that >> either one could be replaced by the other. >> >> Changing all to OF_FLATTREE will touch more files and thus will be a >> bit more obtrusive. It looks like it would take two releases to avoid >> a flag day change. >> >> Changing all to OF_EARLY_FLATTREE can be done in a single release. > > I would get rid of OF_EARLY_FLATREE within the DT core code making it > do nothing more than select OF_FLATTREE. Then the arches can later > just select OF_FLATTREE directly. OK, will do. > But this is all orthogonal to your issue. I think we need to keep the > overlay dependencies on FDT separate. In theory we could support > non-FDT sources or some more complex use that needs to unflatten FDT > themselves. I don't really want to add another user visible kconfig > option (OF_FDT_OVERLAY), so I think as long as we structure things to > support that when needed we're fine. OK, at the "theoretical, what if, keep our options open" level. I'll add the desire to allow future support of non-FDT sources to my general overlay requirements as I propose changes. So far, my proposed patches isolate the FDT source dependency in a single small function, so it seems all is OK from that angle. But all use of overlays for many previous releases requires manually selecting OF_FLATTREE, given that FDTs have been the overlay source. So it seems to make sense for OF_OVERLAY to select OF_FLATTREE (not OF_EARLY_FLATTREE as I mistakenly chose) now. And if future non-FDT overlays are implemented in the future, re-visit how to select OF_FLATTREE in a more granular manner. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
