Add linux build

buildroot-patches/0010-linux-fix-passing-of-host-CFLAGS-and-LDFLAGS.patch

@@ -0,0 +1,46 @@
+
+m ad8804326df075a9935a3751f61e5ad1a2865736 Mon Sep 17 00:00:00 2001
+From: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
+Date: Sun, 4 Mar 2018 22:31:17 +0100
+Subject: [PATCH] linux: fix passing of host CFLAGS and LDFLAGS
+
+We were passing HOSTCFLAGS="$(HOSTCFLAGS)" to Linux. However:
+
+ - HOSTCFLAGS in Buildroot doesn't exist, and is empty, so this
+   assignment never did anything. The name of the variable in
+   Buildroot in HOST_CFLAGS.
+
+ - HOSTCFLAGS in Linux isn't used everywhere, and passing it overrides
+   the default HOSTCFLAGS value defined in the main Linux kernel
+   Makefile.
+
+In addition, there is no way to pass additional host LDFLAGS in the
+Linux kernel build system.
+
+Therefore, we simply shoehorn our HOST_CFLAGS and HOST_LDFLAGS while
+passing HOSTCC to the Linux kernel build system. This has been tested
+to work fine with host OpenSSL and host libelf only available in
+$(HOST_DIR).
+
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
+---
+ linux/linux.mk | 3 +--
+ 1 file changed, 1 insertion(+), 2 deletions(-)
+
+diff --git a/linux/linux.mk b/linux/linux.mk
+index b724b66..7f318a0 100644
+--- a/linux/linux.mk
++++ b/linux/linux.mk
+@@ -99,8 +99,7 @@ LINUX_EXTRA_DOWNLOADS += $(ARCH_XTENSA_OVERLAY_URL)
+ endif
+ 
+ LINUX_MAKE_FLAGS = \
+-	HOSTCC="$(HOSTCC)" \
+-	HOSTCFLAGS="$(HOSTCFLAGS)" \
++	HOSTCC="$(HOSTCC) $(HOST_CFLAGS) $(HOST_LDFLAGS)" \
+ 	ARCH=$(KERNEL_ARCH) \
+ 	INSTALL_MOD_PATH=$(TARGET_DIR) \
+ 	CROSS_COMPILE="$(TARGET_CROSS)" \
+-- 
+2.7.4
+

buildroot/linux/linux.mk

@@ -103,8 +103,7 @@ LINUX_EXTRA_DOWNLOADS += $(ARCH_XTENSA_OVERLAY_URL)
 endif
 
 LINUX_MAKE_FLAGS = \
-	HOSTCC="$(HOSTCC)" \
+	HOSTCC="$(HOSTCC) $(HOST_CFLAGS) $(HOST_LDFLAGS)" \
-	HOSTCFLAGS="$(HOSTCFLAGS)" \
 	ARCH=$(KERNEL_ARCH) \
 	INSTALL_MOD_PATH=$(TARGET_DIR) \
 	CROSS_COMPILE="$(TARGET_CROSS)" \