[PATCH v2 5/5] arm/dom0less: introduce Kconfig for dom0less feature

[Luca Fancellu <luca.fancellu@xxxxxxx>]

Introduce a Kconfig for the dom0less feature, enabled by default,
to be able to choose if the feature should be compiled or not.

Provide static inline stubs when the option is disabled for the
functions externally visible.

Use the new Kconfig to remove dom0less DT binding from the efi-boot.h
code when the Kconfig is not enabled.

Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
---
 xen/arch/arm/Kconfig                      |  9 +++++++++
 xen/arch/arm/Makefile                     |  2 +-
 xen/arch/arm/efi/efi-boot.h               |  4 ++++
 xen/arch/arm/include/asm/dom0less-build.h | 12 ++++++++++++
 4 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index 8dc704e802bc..f84b2cc22d08 100644
--- a/xen/arch/arm/Kconfig
+++ b/xen/arch/arm/Kconfig
@@ -89,6 +89,15 @@ config GICV2
          Driver for the ARM Generic Interrupt Controller v2.
          If unsure, say Y
 
+config DOM0LESS_BOOT
+       bool "Dom0less boot support" if EXPERT
+       depends on ARM
+       default y
+       help
+         Dom0less boot support enables Xen to create and start domU guests 
during
+         Xen boot without the need of a control domain (Dom0), which could be
+         present anyway.
+
 config GICV3
        bool "GICv3 driver"
        depends on !NEW_VGIC
diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
index 89ef0c9075b5..5daf8f10114d 100644
--- a/xen/arch/arm/Makefile
+++ b/xen/arch/arm/Makefile
@@ -15,7 +15,7 @@ obj-y += cpufeature.o
 obj-y += decode.o
 obj-y += device.o
 obj-$(CONFIG_IOREQ_SERVER) += dm.o
-obj-y += dom0less-build.init.o
+obj-$(CONFIG_DOM0LESS_BOOT) += dom0less-build.init.o
 obj-y += domain.o
 obj-y += domain_build.init.o
 obj-$(CONFIG_ARCH_MAP_DOMAIN_PAGE) += domain_page.o
diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
index 1c3640bb65fd..689dc016d081 100644
--- a/xen/arch/arm/efi/efi-boot.h
+++ b/xen/arch/arm/efi/efi-boot.h
@@ -802,6 +802,7 @@ static int __init handle_module_node(const EFI_LOADED_IMAGE 
*loaded_image,
     return 1;
 }
 
+#ifdef CONFIG_DOM0LESS_BOOT
 /*
  * This function checks for boot modules under the domU guest domain node
  * in the DT.
@@ -849,6 +850,7 @@ static int __init handle_dom0less_domain_node(const 
EFI_LOADED_IMAGE *loaded_ima
 
     return mb_modules_found;
 }
+#endif
 
 /*
  * This function checks for xen domain nodes under the /chosen node for 
possible
@@ -876,6 +878,7 @@ static int __init efi_check_dt_boot(const EFI_LOADED_IMAGE 
*loaded_image)
     {
         int ret;
 
+#ifdef CONFIG_DOM0LESS_BOOT
         if ( !fdt_node_check_compatible(fdt_efi, node, "xen,domain") )
         {
             /* Found a node with compatible xen,domain; handle this node. */
@@ -884,6 +887,7 @@ static int __init efi_check_dt_boot(const EFI_LOADED_IMAGE 
*loaded_image)
                 return ERROR_DT_MODULE_DOMU;
         }
         else
+#endif
         {
             ret = handle_module_node(loaded_image, &dir_handle, node, addr_len,
                                      size_len, false);
diff --git a/xen/arch/arm/include/asm/dom0less-build.h 
b/xen/arch/arm/include/asm/dom0less-build.h
index d95cb6234b62..859944eece16 100644
--- a/xen/arch/arm/include/asm/dom0less-build.h
+++ b/xen/arch/arm/include/asm/dom0less-build.h
@@ -8,9 +8,21 @@
 #ifndef __ARM_DOM0LESS_BUILD_H_
 #define __ARM_DOM0LESS_BUILD_H_
 
+#ifdef CONFIG_DOM0LESS_BOOT
+
 void create_domUs(void);
 bool is_dom0less_mode(void);
 
+#else  /* !CONFIG_DOM0LESS_BOOT */
+
+static inline void create_domUs(void) {}
+static inline bool is_dom0less_mode(void)
+{
+    return false;
+}
+
+#endif /* CONFIG_DOM0LESS_BOOT */
+
 #endif  /* __ARM_DOM0LESS_BUILD_H_ */
 
 /*
-- 
2.34.1