[PATCH] fdt: Allow OF_HAS_PRIOR_STAGE to be disabled in defconfig

[Tom Rini]

On Fri, Apr 04, 2025 at 09:40:18AM +1300, Simon Glass wrote:
> Hi Tom,
> 
> On Fri, 4 Apr 2025 at 08:02, Tom Rini <trini at konsulko.com> wrote:
> >
> > On Fri, Apr 04, 2025 at 06:53:49AM +1300, Simon Glass wrote:
> >
> > > At present it is impossible to change the qemu_arm64 defconfig to
> > > obtain a devicetree from the U-Boot build.
> > >
> > > This is necessary for FIT validation, for example, where the signature
> > > node must be compiled into U-Boot.
> > >
> > > A proposed change to QEMU has been blocked for several years. As a
> > > workaround, the only option is to use QEMU's dumpdtb option, merge in
> > > the signature node manually and then disable OF_HAS_PRIOR_STAGE
> > >
> > > Unfortunately the only way to disable OF_HAS_PRIOR_STAGE at present is
> > > to hack the Kconfig. So update it to allow use from defconfig. This
> > > avoids needing to patch U-Boot to get this working.
> > >
> > > Signed-off-by: Simon Glass <sjg at chromium.org>
> > > Link: https://patchwork.kernel.org/project/qemu-devel/patch/20210926183410.256484-1-sjg@chromium.org/#24481799
> >
> > How about instead we do something like:
> > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> > index b7311d3b754b..44e45a304cd0 100644
> > --- a/arch/arm/Kconfig
> > +++ b/arch/arm/Kconfig
> > @@ -1080,7 +1080,7 @@ config ARCH_QEMU
> >         imply DM_RNG
> >         imply DM_RTC
> >         imply RTC_PL031
> > -       imply OF_HAS_PRIOR_STAGE if !TARGET_QEMU_ARM_SBSA
> > +       imply OF_HAS_PRIOR_STAGE if !QEMU_MANUAL_DTB
> >         imply VIDEO
> >         imply VIDEO_BOCHS
> >         imply SYS_WHITE_ON_BLACK
> > diff --git a/board/emulation/common/Kconfig b/board/emulation/common/Kconfig
> > index 4c15c8bcb891..9053f2ff2f55 100644
> > --- a/board/emulation/common/Kconfig
> > +++ b/board/emulation/common/Kconfig
> > @@ -13,3 +13,10 @@ config MTDPARTS_NOR1
> >         help
> >           This define the partition of nor1 used to build mtparts dynamically
> >           for the u-boot env stored on nor1.
> > +
> > +config QEMU_MANUAL_DTB
> > +       bool "Manually provide a device tree to QEMU"
> > +       depends on ARCH_QEMU # Expand more if needed
> > +       help
> > +         For some use cases, such as FIT validation of U-Boot itself we need
> > +         to override the device tree that QEMU would normally provide to us.
> >
> > This way we don't start opening asking OF_HAS_PRIOR_STAGE.
> 
> Yes that seems fine, thanks. If it ends up becoming a more general
> problem we can worry about it then.

Thanks. I'll let you make that up in to a more general and complete
patch, that was just me poking at the files for a moment.

-- 
Tom
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