Make iasl option check work with older versions of iasl.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

diff --git a/Makefile b/Makefile
index 72ee15289a9bb9ecbc2f12c28a74417d6326bee4..45ea48a49157fd8a66c31e67643c5f20856462b5 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -221,7 +221,7 @@ $(OUT)vgabios.bin: $(OUT)vgabios.bin.raw tools/buildrom.py
 
 ################ DSDT build rules
 
-iasl-option=$(shell if "$(1)" "$(2)" -h > /dev/null 2>&1 \
+iasl-option=$(shell if test -z "`$(1) $(2) 2>&1 > /dev/null`" \
     ; then echo "$(2)"; else echo "$(3)"; fi ;)
 
 $(OUT)%.hex: src/%.dsl ./tools/acpi_extract_preprocess.py ./tools/acpi_extract.py