On Thu, Jan 04, 2018 at 08:39:38PM -0600, Kyle Evans wrote: > On Thu, Jan 4, 2018 at 7:55 PM, Frank Rowand <frowand.list@xxxxxxxxx> wrote: > > On 01/04/18 13:47, Kyle Evans wrote: > >> On Thu, Jan 4, 2018 at 3:34 PM, Kyle Evans <kevans@xxxxxxxxxxx> wrote: > >>> On Thu, Jan 4, 2018 at 2:41 PM, Kyle Evans <kevans@xxxxxxxxxxx> wrote: > >>>> On Thu, Jan 4, 2018 at 2:33 PM, Frank Rowand <frowand.list@xxxxxxxxx> wrote: > >>>>> [... snip ...] > >>>>> > >>>>> Does this remove the need for the proposed patch, or am I still > >>>>> missing something? > >>>> > >>>> ... nope. Apparently I never tested this with this particular dtc(1) > >>>> and instead just assumed it did the same as ours- allocate phandle > >>>> sparsely, even with -@. That certainly removes the need for this > >>>> patch, and I'm somewhat upset that I hadn't previously considered > >>>> this. > >>>> > >>>> @David, Jon: Please disregard all of the patches along these lines... > >>>> I'll fix this in our dtc, where it should be fixed. > >>>> > >>>> Thanks, Frank! > >>> > >>> Actually, I'm kind of torn on whether this is useful or not. With > >>> being able to have EFI-provided FDT, it's hard to guarantee whether > >>> the FDT we're provided has been compiled with GPL dtc(1) and -@. The > >>> above solves this problem for most of my personal use-cases , though, > >>> since I can guarantee that our FDT and U-Boot provided FDT is compiled > >>> properly. > >> > >> Apologies for the triple post; I realized that this argument is > >> inherently wrong, since we can't reference the node if there's no > >> symbol anyways. > >> > >> The only way this might still be a good idea is to support more > >> minimal cases where an implementation might prefer to not create a > >> phandle for nodes that haven't been referenced. > >> > >> In our case, we have a function [1] that walks the tree and generates > >> metadata on nodes that have phandles, under the assumption that these > >> have been referenced somewhere and provides a way to more quickly > >> reference these specifically through a separate linked link. > >> Allocating phandles for everything as GPL dtc does adds quite a bit > >> more overhead to this. > >> > >> [1] http://src.illumos.org/source/xref/freebsd-head/sys/dev/ofw/openfirm.c#119 > > > > The "-@" option does not add a phandle to _every_ node, just to nodes > > that have a label: > > > > In practice, this is still a not necessarily close superset of those > that are actually going to actually get referenced in a given .dts. I > note that a number of nodes will still get labelled that are unlikely > to be referenced for any number of reasons. > > For instance, as an example [1][2][3] of one of the boards I'm working > on currently, all of the ehci/ohci/mmc nodes, some set of the pio > nodes... almost every single node has a label, and most of them don't > need a phandle based on what is currently referenced and actually > used. I note that 27 of these nodes seem to be referenced, out of 39 > nodes with labels (numbers are approximate), leaving ~30% (12) of > labelled nodes unreferenced. > > For a slightly larger example, [4][5][6][7]; 74 referenced nodes out > of 113 labelled nodes, leaving ~35% (39) of labelled nodes > unreferenced. Right, but what I'm not getting is why having a lot of symbols is a bad thing, other than because of a FreeBSD internal detail. > > This is only bothersome because it starts adding up as these things > get bigger, and I don't think it really needs to. The alternative to > keep phandles down to the minimum set required doesn't add much in > maintenance cost or overhead from the overlay application side; > especially for blobs generated by this dtc(1) that make the active > decision to allocate liberally rather than conservatively. > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/sun8i-a83t-bananapi-m3.dts > [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/sun8i-a83t.dtsi > [3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/sunxi-common-regulators.dtsi > > [4] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/am335x-bonegreen.dts > [5] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/am33xx.dtsi > [6] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/am335x-bone-common.dtsi > [7] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/am335x-bonegreen-common.dtsi -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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