Re: [PATCH v4 12/12] xen/dt: Remove DOM0LESS_BOOT's requirement on HAS_DEVICE_TREE_DISCOVERY

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 20 Jun 2025, Alejandro Vallejo wrote:
> This effectively means that DOM0LESS_BOOT on platforms without
> HAS_DEVICE_TREE_DISCOVERY (i.e: x86) acts as a selector for a
> stripped-down version of DT code.
> 
> Signed-off-by: Alejandro Vallejo <agarciav@xxxxxxx>

This is so much better than before. Thank you and all the reviewers for
making the integration so much smoother. This patch is so much simpler
and readable compared to before.

I think we need to plan for renaming DOM0LESS_BOOT into something
better, such as PREDEFINED_DOMS, but I would keep it as a separate
patch in any case. So I think this is OK for now.

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>  xen/Kconfig.debug               | 2 +-
>  xen/common/Kconfig              | 3 ++-
>  xen/common/Makefile             | 1 +
>  xen/common/device-tree/Makefile | 8 ++++----
>  4 files changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/xen/Kconfig.debug b/xen/Kconfig.debug
> index 9192d593a7..89b0af53a2 100644
> --- a/xen/Kconfig.debug
> +++ b/xen/Kconfig.debug
> @@ -92,7 +92,7 @@ config VERBOSE_DEBUG
>  
>  config DEVICE_TREE_DEBUG
>       bool "Device tree debug messages"
> -     depends on HAS_DEVICE_TREE_DISCOVERY
> +     depends on DOM0LESS_BOOT || HAS_DEVICE_TREE_DISCOVERY
>       help
>         Device tree parsing and DOM0 device tree building messages are
>         logged in the Xen ring buffer.
> diff --git a/xen/common/Kconfig b/xen/common/Kconfig
> index 6294cd7939..1ac28a4e78 100644
> --- a/xen/common/Kconfig
> +++ b/xen/common/Kconfig
> @@ -14,7 +14,8 @@ config CORE_PARKING
>  
>  config DOM0LESS_BOOT
>       bool "Dom0less boot support" if EXPERT
> -     depends on HAS_DOM0LESS && HAS_DEVICE_TREE_DISCOVERY && 
> DOMAIN_BUILD_HELPERS
> +     select LIBFDT
> +     depends on HAS_DOM0LESS && DOMAIN_BUILD_HELPERS
>       default y
>       help
>         Dom0less boot support enables Xen to create and start domU guests 
> during
> diff --git a/xen/common/Makefile b/xen/common/Makefile
> index d541fbcf49..19d6ff7a90 100644
> --- a/xen/common/Makefile
> +++ b/xen/common/Makefile
> @@ -9,6 +9,7 @@ obj-$(CONFIG_DEBUG_TRACE) += debugtrace.o
>  obj-$(CONFIG_HAS_DEVICE_TREE_DISCOVERY) += device.o
>  obj-$(filter-out $(CONFIG_X86),$(CONFIG_ACPI)) += device.o
>  obj-$(CONFIG_HAS_DEVICE_TREE_DISCOVERY) += device-tree/
> +obj-$(CONFIG_DOM0LESS_BOOT) += device-tree/

nice trick


>  obj-$(CONFIG_IOREQ_SERVER) += dm.o
>  obj-y += domain.o
>  obj-y += event_2l.o
> diff --git a/xen/common/device-tree/Makefile b/xen/common/device-tree/Makefile
> index 8abc069c4b..4a10b0508f 100644
> --- a/xen/common/device-tree/Makefile
> +++ b/xen/common/device-tree/Makefile
> @@ -1,11 +1,11 @@
>  obj-y += bootfdt.init.o
> -obj-y += bootinfo-fdt.init.o
> -obj-y += bootinfo.init.o
> -obj-y += device-tree.o
> +obj-$(CONFIG_HAS_DEVICE_TREE_DISCOVERY) += bootinfo-fdt.init.o
> +obj-$(CONFIG_HAS_DEVICE_TREE_DISCOVERY) += bootinfo.init.o
> +obj-$(CONFIG_HAS_DEVICE_TREE_DISCOVERY) += device-tree.o
>  obj-$(CONFIG_DOMAIN_BUILD_HELPERS) += domain-build.init.o
>  obj-$(CONFIG_DOM0LESS_BOOT) += dom0less-build.init.o
>  obj-$(CONFIG_OVERLAY_DTB) += dt-overlay.o
> -obj-y += intc.o
> +obj-$(CONFIG_HAS_DEVICE_TREE_DISCOVERY) += intc.o
>  obj-$(CONFIG_DOMAIN_BUILD_HELPERS) += kernel.o
>  obj-$(CONFIG_STATIC_EVTCHN) += static-evtchn.init.o
>  obj-$(CONFIG_STATIC_MEMORY) += static-memory.init.o
> -- 
> 2.43.0
>