submitted as: https://review.spdk.io/gerrit/c/spdk/spdk/+/14996

--- a/CONFIG
+++ b/CONFIG
@@ -158,6 +158,9 @@
 
 # Build ISA-L library
 CONFIG_ISAL=y
+CONFIG_ISAL_INC_DIR=
+CONFIG_ISAL_LIB_DIR=
+CONFIG_ISAL_PKG_CONFIG=n
 
 # Build with IO_URING support
 CONFIG_URING=n
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,9 @@
 DIRS-$(CONFIG_APPS) += app
 DIRS-y += test
 DIRS-$(CONFIG_IPSEC_MB) += ipsecbuild
+ifneq ($(CONFIG_ISAL_PKG_CONFIG),y)
 DIRS-$(CONFIG_ISAL) += isalbuild
+endif
 DIRS-$(CONFIG_VFIO_USER) += vfiouserbuild
 DIRS-y += python
 DIRS-$(CONFIG_XNVME) += xnvmebuild
@@ -58,10 +60,12 @@
 DPDK_DEPS += ipsecbuild
 endif
 
+ifneq ($(CONFIG_ISAL_PKG_CONFIG),y)
 ifeq ($(CONFIG_ISAL),y)
 ISALBUILD = isalbuild
 LIB += isalbuild
 DPDK_DEPS += isalbuild
+endif
 endif
 
 ifeq ($(CONFIG_VFIO_USER),y)
--- a/configure
+++ b/configure
@@ -52,6 +52,8 @@
 	echo "                           Implies --without-dpdk."
 	echo " --with-idxd               Build the IDXD library and accel framework plug-in module."
 	echo " --without-idxd            Disabled while experimental. Only built for x86 when enabled."
+	echo " --with-isal               Build against a system isa-l version. By default, the isa-l"
+	echo "                           submodule in spdk tree will be used."
 	echo " --with-crypto             Build vbdev crypto module."
 	echo " --without-crypto          No path required."
 	echo " --with-fio[=DIR]          Build fio_plugin."
@@ -421,6 +423,22 @@
 		--without-dpdk)
 			CONFIG[DPDK_DIR]=
 			;;
+		--with-isal)
+			# Can we use pkg-config?
+			if command -v "pkg-config" > /dev/null 2>&1 && pkg-config --exists libisal; then
+				isal_libdir=$(pkg-config --variable=libdir libisal)
+				isal_libdir=$(readlink -f $isal_libdir)
+				isal_incdir=$(pkg-config --variable=includedir libisal)
+				echo "Using isa-l lib dir $isal_libdir"
+				CONFIG[ISAL_LIB_DIR]=$isal_libdir
+				CONFIG[ISAL_INC_DIR]=$isal_incdir
+				CONFIG[ISAL_PKG_CONFIG]=y
+				CFLAGS="${CFLAGS:+$CFLAGS }$(pkg-config --cflags libisal)"
+			else
+				echo "libisal.pc not found, aborting"
+				exit 1
+			fi
+			;;
 		--with-wpdk=*)
 			check_dir "$i"
 			CONFIG[WPDK_DIR]=$(readlink -f ${i#*=})
@@ -1113,50 +1131,55 @@
 	exit 1
 fi
 
-if [[ $arch == x86_64* ]] || [[ $arch == aarch64* ]]; then
+if [[ "${CONFIG[ISAL_PKG_CONFIG]}" = "y" ]]; then
+	echo "Using system ISA-L"
 	CONFIG[ISAL]=y
-	# make sure the submodule is initialized
-	if [ ! -f "$rootdir"/isa-l/autogen.sh ]; then
-		echo "ISA-L is required but was not found, please init the submodule with:"
-		echo "  git submodule update --init"
-		echo "and then re-run this script."
-		exit 1
-	fi
-	# for x86 only, check the nasm version for ISA-L and IPSEC
-	if [[ $arch == x86_64* ]]; then
-		ver=$(nasm -v 2> /dev/null | awk '{print $3}' | awk -Fr '{print $1}')
-		if lt "$ver" 2.14; then
-			CONFIG[ISAL]=n
-			# IPSEC has nasm requirement and DPDK crypto relies on IPSEC
-			CONFIG[IPSEC_MB]=n
-			echo "WARNING: ISA-L & DPDK crypto cannot be used as nasm ver must be 2.14 or newer."
+else
+	if [[ $arch == x86_64* ]] || [[ $arch == aarch64* ]]; then
+		CONFIG[ISAL]=y
+		# make sure the submodule is initialized
+		if [ ! -f "$rootdir"/isa-l/autogen.sh ]; then
+			echo "ISA-L is required but was not found, please init the submodule with:"
+			echo "  git submodule update --init"
+			echo "and then re-run this script."
+			exit 1
 		fi
+		# for x86 only, check the nasm version for ISA-L and IPSEC
+		if [[ $arch == x86_64* ]]; then
+			ver=$(nasm -v 2> /dev/null | awk '{print $3}' | awk -Fr '{print $1}')
+			if lt "$ver" 2.14; then
+				CONFIG[ISAL]=n
+				# IPSEC has nasm requirement and DPDK crypto relies on IPSEC
+				CONFIG[IPSEC_MB]=n
+				echo "WARNING: ISA-L & DPDK crypto cannot be used as nasm ver must be 2.14 or newer."
+			fi
+		fi
+	else
+		# for PPC
+		CONFIG[ISAL]=n
+		echo "WARNING: ISA-L cannot be used due to architecture incompatibility."
 	fi
-else
-	# for PPC
-	CONFIG[ISAL]=n
-	echo "WARNING: ISA-L cannot be used due to architecture incompatibility."
-fi
 
-# now either configure ISA-L or disable unavailable features
-if [[ "${CONFIG[ISAL]}" = "y" ]]; then
-	cd $rootdir/isa-l
-	ISAL_LOG=$rootdir/isa-l/spdk-isal.log
-	if [[ -n "${CONFIG[CROSS_PREFIX]}" ]]; then
-		ISAL_OPTS=("--host=${CONFIG[CROSS_PREFIX]}")
+	# now either configure ISA-L or disable unavailable features
+	if [[ "${CONFIG[ISAL]}" = "y" ]]; then
+		cd $rootdir/isa-l
+		ISAL_LOG=$rootdir/isa-l/spdk-isal.log
+		if [[ -n "${CONFIG[CROSS_PREFIX]}" ]]; then
+			ISAL_OPTS=("--host=${CONFIG[CROSS_PREFIX]}")
+		else
+			ISAL_OPTS=()
+		fi
+		echo -n "Configuring ISA-L (logfile: $ISAL_LOG)..."
+		./autogen.sh &> $ISAL_LOG
+		./configure CFLAGS="-fPIC -g -O2" "${ISAL_OPTS[@]}" --enable-shared=no >> $ISAL_LOG 2>&1
+		echo "done."
+		cd $rootdir
 	else
-		ISAL_OPTS=()
+		echo "Without ISA-L, there is no software support for crypto or compression,"
+		echo "so these features will be disabled."
+		CONFIG[CRYPTO]=n
+		CONFIG[REDUCE]=n
 	fi
-	echo -n "Configuring ISA-L (logfile: $ISAL_LOG)..."
-	./autogen.sh &> $ISAL_LOG
-	./configure CFLAGS="-fPIC -g -O2" "${ISAL_OPTS[@]}" --enable-shared=no >> $ISAL_LOG 2>&1
-	echo "done."
-	cd $rootdir
-else
-	echo "Without ISA-L, there is no software support for crypto or compression,"
-	echo "so these features will be disabled."
-	CONFIG[CRYPTO]=n
-	CONFIG[REDUCE]=n
 fi
 
 if [[ "${CONFIG[SMA]}" = "y" ]]; then
--- a/lib/accel/accel_sw.c
+++ b/lib/accel/accel_sw.c
@@ -20,7 +20,11 @@
 #endif
 
 #ifdef SPDK_CONFIG_ISAL
+#ifndef SPDK_CONFIG_ISAL_PKG_CONFIG
 #include "../isa-l/include/igzip_lib.h"
+#else
+#include "isa-l/igzip_lib.h"
+#endif
 #endif
 
 struct sw_accel_io_channel {
--- a/lib/util/crc16.c
+++ b/lib/util/crc16.c
@@ -11,7 +11,11 @@
  */
 
 #ifdef SPDK_CONFIG_ISAL
+#ifndef SPDK_CONFIG_ISAL_PKG_CONFIG
 #include "isa-l/include/crc.h"
+#else
+#include "isa-l/crc.h"
+#endif
 
 uint16_t
 spdk_crc16_t10dif(uint16_t init_crc, const void *buf, size_t len)
--- a/lib/util/crc32c.c
+++ b/lib/util/crc32c.c
@@ -8,7 +8,11 @@
 
 #ifdef SPDK_CONFIG_ISAL
 #define SPDK_HAVE_ISAL
+#ifndef SPDK_CONFIG_ISAL_PKG_CONFIG
 #include <isa-l/include/crc.h>
+#else
+#include <isa-l/crc.h>
+#endif
 #elif defined(__aarch64__) && defined(__ARM_FEATURE_CRC32)
 #define SPDK_HAVE_ARM_CRC
 #include <arm_acle.h>
--- a/lib/util/xor.c
+++ b/lib/util/xor.c
@@ -85,7 +85,11 @@
 }
 
 #ifdef SPDK_CONFIG_ISAL
+#ifndef SPDK_CONFIG_ISAL_PKG_CONFIG
 #include "isa-l/include/raid.h"
+#else
+#include "isa-l/raid.h"
+#endif
 
 #define SPDK_XOR_BUF_ALIGN 32