[PATCH 4/4] livepatch: differentiate between old and new build systems

[Roger Pau Monne <roger.pau@citrix.com>]

Do not attempt to modify the build system if CFLAGS are not set in
Rules.mk, and instead rely on CONFIG_LIVEPATCH already setting
-f{function,data}-sections.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
This depends on getting the patch to add -f{function,data}-sections
when using CONFIG_LIVEPATCH accepted.
---
 livepatch-build | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/livepatch-build b/livepatch-build
index 38a92be..656cdac 100755
--- a/livepatch-build
+++ b/livepatch-build
@@ -98,14 +98,20 @@ function build_special()
 
     # Build with special GCC flags
     cd "${SRCDIR}/xen" || die
-    sed -i 's/CFLAGS += -nostdinc/CFLAGS += -nostdinc -ffunction-sections -fdata-sections/' Rules.mk
-    cp -p arch/x86/Makefile arch/x86/Makefile.bak
-    sed -i 's/--section-alignment=0x200000/--section-alignment=0x1000/' arch/x86/Makefile
-    # Restore timestamps to prevent spurious rebuilding
-    touch --reference=arch/x86/Makefile.bak arch/x86/Makefile
-    make "-j$CPUS" $XEN_DEBUG &> "${OUTPUT}/build_${name}_compile.log" || die
-    sed -i 's/CFLAGS += -nostdinc -ffunction-sections -fdata-sections/CFLAGS += -nostdinc/' Rules.mk
-    mv -f arch/x86/Makefile.bak arch/x86/Makefile
+    if grep -q 'nostdinc' Rules.mk; then
+         # Support for old build system, attempt to set -f{function,data}-sections and rebuild
+        sed -i 's/CFLAGS += -nostdinc/CFLAGS += -nostdinc -ffunction-sections -fdata-sections/' Rules.mk
+        cp -p arch/x86/Makefile arch/x86/Makefile.bak
+        sed -i 's/--section-alignment=0x200000/--section-alignment=0x1000/' arch/x86/Makefile
+        # Restore timestamps to prevent spurious rebuilding
+        touch --reference=arch/x86/Makefile.bak arch/x86/Makefile
+        make "-j$CPUS" $XEN_DEBUG &> "${OUTPUT}/build_${name}_compile.log" || die
+        sed -i 's/CFLAGS += -nostdinc -ffunction-sections -fdata-sections/CFLAGS += -nostdinc/' Rules.mk
+        mv -f arch/x86/Makefile.bak arch/x86/Makefile
+    else
+        # -f{function,data}-sections set by CONFIG_LIVEPATCH
+        make "-j$CPUS" $XEN_DEBUG &> "${OUTPUT}/build_${name}_compile.log" || die
+    fi
 
     unset LIVEPATCH_BUILD_DIR
     unset LIVEPATCH_CAPTURE_DIR
-- 
2.34.1