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Bug#910727: Overlays cannot be applied to dtbs - missing DTC_FLAGS='-@'

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On Mon, Jul 31, 2023 at 10:03:52AM +0200, Diederik de Haas wrote:
> On Monday, 31 July 2023 04:28:31 CEST MOESSBAUER, Felix wrote:
> > On Sun, 12 Feb 2023 18:52:07 +0100 Nicolas Frattaroli
> > <frattaroli.nicolas@gmail.com> wrote:
> > > I realise this is quite an old bug, but it would still be of interest
> > > to me to get this enabled. The -@ option will increase the size of
> > > the compiled device tree blobs somewhat, but on the flipside, 
> > > u-boot-menu's device tree overlay functionality will actually be useful.
> > 
> > The increase is around 30% in average. For the linux-image-6.1.0-10-
> > arm64, we have around 30MB of dtb files (uncompressed). By that, the
> > package would grow by 10MB (uncompressed) or even less when compressed.
> 
> I'm not a kernel maintainer, but I wouldn't expect it to be applied to 
> Debian's Stable kernel, ie the 6.1 series.
> 
> > On many (if not most) arm based boards, these device tree overlays are
> > very useful. There are also many kernel patches about enabling the
> > symbol support on a per-device basis. However, kernel devs seem to have
> > some mixed feelings about that. A proposed solution is to enable this
> > at distro level [1].
> > @Ben: Would it be an accepted solution to enable the DTC_FLAGS += -@
> > for all armhf, armmp, arm64 and riscv devices?
> 
> AFAIUI, the upstream kernel devs were against such a blanket enablement.
> (Consequently it sounds like a bad idea if Debian would do it)
> 
> https://lore.kernel.org/all/20220328000915.15041-1-ansuelsmth@gmail.com/ was a 
> renewed attempt at restructuring the various .dts* into vendor directories and 
> with 6.5 that got merged into the upstream kernel.
> And (AFAIUI) that was seen as a prerequisite to start enabling the "-@" flag on 
> a vendor/directory level, with optionally a subselection if it didn't make 
> sense to enable it for all boards ... pretty much (exactly) as you proposed.
> 
> Doing it at the distro level was rejected (at least for Debian) with the 
> argument that it should be done upstream.
> As there is some (?) coordination/synchronization wrt DeviceTrees between the 
> upstream kernel and u-boot, that also seems required for the functionality 
> quoted at the top of this email.
> 
> You mentioned you proposed it for RISC-V boards and some DDs proposed it for 
> RPi boards and both got accepted. I think/expected that we would see (many?) 
> more such patches getting accepted going forward now that the above mentioned 
> dts directory restructuring has taken place.
> 
> IOW: I agree with the reasoning you brought up in your patch submission thread 
> and keep targeting inclusion in the upstream kernel.

Was there progress here, or what should we further do? If it's not
something which is going to land upstream then I would suggest that we
close the bug.

Regards,
Salvatore

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Bug#910727: Overlays cannot be applied to dtbs - missing DTC_FLAGS='-@' Salvatore Bonaccorso <carnil@debian.org> - 2025-04-25 11:20 +0200
  Processed: Re: Bug#910727: Overlays cannot be applied to dtbs -  missing DTC_FLAGS='-@' "Debian Bug Tracking System" <owner@bugs.debian.org> - 2025-04-25 11:20 +0200
  Bug#910727: Overlays cannot be applied to dtbs - missing DTC_FLAGS='-@' "Diederik de Haas" <didi.debian@cknow.org> - 2025-04-25 12:30 +0200

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