[PATCH v1] kbuild: Allow building of samples with UML

["Mickaël Salaün" <mic@digikod.net>]

It's useful to build samples/* with UML and the only blocker is the
artificial incompatibility with CONFIG_HEADERS_INSTALL.

Allow the headers_install target with ARCH=um, which then allow building
samples (and tests using them) with UML too:

  printf 'CONFIG_SAMPLES=y\nCONFIG_HEADERS_INSTALL=y\nCONFIG_SAMPLE_LANDLOCK=y\n' >.config
  make ARCH=um olddefconfig headers_install
  make ARCH=um samples/landlock/

Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicolas Schier <nicolas@fjasle.eu>
Cc: Richard Weinberger <richard@nod.at>
Fixes: 1b620d539ccc ("kbuild: disable header exports for UML in a straightforward way")
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---
 Makefile          | 1 -
 lib/Kconfig.debug | 1 -
 2 files changed, 2 deletions(-)

diff --git a/Makefile b/Makefile
index e5b8a8832c0c..6e2cce16a2a3 100644
--- a/Makefile
+++ b/Makefile
@@ -1355,7 +1355,6 @@ hdr-inst := -f $(srctree)/scripts/Makefile.headersinst obj
 
 PHONY += headers
 headers: $(version_h) scripts_unifdef uapi-asm-generic archheaders archscripts
-	$(if $(filter um, $(SRCARCH)), $(error Headers not exportable for UML))
 	$(Q)$(MAKE) $(hdr-inst)=include/uapi
 	$(Q)$(MAKE) $(hdr-inst)=arch/$(SRCARCH)/include/uapi
 
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index f3d723705879..fac1208f48e4 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -473,7 +473,6 @@ config READABLE_ASM
 
 config HEADERS_INSTALL
 	bool "Install uapi headers to usr/include"
-	depends on !UML
 	help
 	  This option will install uapi headers (headers exported to user-space)
 	  into the usr/include directory for use during the kernel build.
-- 
2.47.1