build: Allow the user to set target architecture in configure

Change-Id: I7f2a1464c0c8872e5e7856a830aaf7ea8cdf4e81
Signed-off-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/463013
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>

CONFIG

@@ -34,6 +34,9 @@
 # Installation prefix
 CONFIG_PREFIX="/usr/local"
 
+# Target architecture
+CONFIG_ARCH=native
+
 # Build with debug logging. Turn off for performance testing and normal usage
 CONFIG_DEBUG=n
 

configure

@@ -16,6 +16,7 @@ function usage()
 	echo " -h, --help                Display this help and exit"
 	echo ""
 	echo " --prefix=path             Configure installation prefix (default: /usr/local)"
+	echo " --target-arch=arch        Target build architecture. Must be a valid GNU arch. Default: native"
 	echo ""
 	echo " --enable-debug            Configure for debug builds"
 	echo " --enable-log-bt           Enable support of backtrace printing in SPDK logs (requires libunwind)."
@@ -119,6 +120,9 @@ for i in "$@"; do
 		--prefix=*)
 			CONFIG[PREFIX]="${i#*=}"
 			;;
+		--target-arch=*)
+			CONFIG[ARCH]="${i#*=}"
+			;;
 		--enable-debug)
 			CONFIG[DEBUG]=y
 			;;

mk/spdk.common.mk

@@ -72,7 +72,7 @@ ifneq ($(filter freebsd%,$(TARGET_TRIPLET_WORDS)),)
 OS = FreeBSD
 endif
 
-TARGET_ARCHITECTURE ?= native
+TARGET_ARCHITECTURE ?= $(CONFIG_ARCH)
 TARGET_MACHINE := $(firstword $(TARGET_TRIPLET_WORDS))
 
 COMMON_CFLAGS = -g $(C_OPT) -Wall -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wmissing-declarations -fno-strict-aliasing -I$(SPDK_ROOT_DIR)/include