[v7,01/13] eal: add option register infrastructure

diff --git a/lib/librte_eal/bsdapp/eal/Makefile b/lib/librte_eal/bsdapp/eal/Makefile
index d19f53c..bfeddaa 100644
--- a/lib/librte_eal/bsdapp/eal/Makefile
+++ b/lib/librte_eal/bsdapp/eal/Makefile
@@ -67,6 +67,7 @@  SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += malloc_elem.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += malloc_heap.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += malloc_mp.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += rte_keepalive.c
+SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += rte_option.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += rte_service.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += rte_reciprocal.c
 
diff --git a/lib/librte_eal/bsdapp/eal/eal.c b/lib/librte_eal/bsdapp/eal/eal.c
index 7735194..178cfd6 100644
--- a/lib/librte_eal/bsdapp/eal/eal.c
+++ b/lib/librte_eal/bsdapp/eal/eal.c
@@ -42,6 +42,7 @@ 
 #include <rte_devargs.h>
 #include <rte_version.h>
 #include <rte_vfio.h>
+#include <rte_option.h>
 #include <rte_atomic.h>
 #include <malloc_heap.h>
 
@@ -414,12 +415,20 @@  eal_parse_args(int argc, char **argv)
 	argvopt = argv;
 	optind = 1;
 	optreset = 1;
+	opterr = 0;
 
 	while ((opt = getopt_long(argc, argvopt, eal_short_options,
 				  eal_long_options, &option_index)) != EOF) {
 
-		/* getopt is not happy, stop right now */
+		/*
+		 * getopt didn't recognise the option, lets parse the
+		 * registered options to see if the flag is valid
+		 */
 		if (opt == '?') {
+			ret = rte_option_parse(argv[optind-1]);
+			if (ret == 0)
+				continue;
+
 			eal_usage(prgname);
 			ret = -1;
 			goto out;
@@ -791,6 +800,9 @@  rte_eal_init(int argc, char **argv)
 
 	rte_eal_mcfg_complete();
 
+	/* Call each registered callback, if enabled */
+	rte_option_init();
+
 	return fctret;
 }
 
diff --git a/lib/librte_eal/common/Makefile b/lib/librte_eal/common/Makefile
index cca6882..87d8c45 100644
--- a/lib/librte_eal/common/Makefile
+++ b/lib/librte_eal/common/Makefile
@@ -12,6 +12,7 @@  INC += rte_tailq.h rte_interrupts.h rte_alarm.h
 INC += rte_string_fns.h rte_version.h
 INC += rte_eal_memconfig.h rte_malloc_heap.h
 INC += rte_hexdump.h rte_devargs.h rte_bus.h rte_dev.h rte_class.h
+INC += rte_option.h
 INC += rte_pci_dev_feature_defs.h rte_pci_dev_features.h
 INC += rte_malloc.h rte_keepalive.h rte_time.h
 INC += rte_service.h rte_service_component.h
diff --git a/lib/librte_eal/common/eal_private.h b/lib/librte_eal/common/eal_private.h
index b189d67..442c6dc 100644
--- a/lib/librte_eal/common/eal_private.h
+++ b/lib/librte_eal/common/eal_private.h
@@ -349,4 +349,25 @@  dev_sigbus_handler_register(void);
 int
 dev_sigbus_handler_unregister(void);
 
+/**
+ * Check if the option is registered.
+ *
+ * @param option
+ *  The option to be parsed.
+ *
+ * @return
+ *  0 on success
+ * @return
+ *  -1 on fail
+ */
+int
+rte_option_parse(const char *opt);
+
+/**
+ * Iterate through the registered options and execute the associated
+ * callback if enabled.
+ */
+void
+rte_option_init(void);
+
 #endif /* _EAL_PRIVATE_H_ */
diff --git a/lib/librte_eal/common/include/rte_option.h b/lib/librte_eal/common/include/rte_option.h
new file mode 100644
index 0000000..8957b97
--- /dev/null
+++ b/lib/librte_eal/common/include/rte_option.h
@@ -0,0 +1,63 @@ 
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2018 Intel Corporation.
+ */
+
+#ifndef __INCLUDE_RTE_OPTION_H__
+#define __INCLUDE_RTE_OPTION_H__
+
+/**
+ * @file
+ *
+ * This API offers the ability to register options to the EAL command line and
+ * map those options to functions that will be executed at the end of EAL
+ * initialization. These options will be available as part of the EAL command
+ * line of applications and are dynamically managed.
+ *
+ * This is used primarily by DPDK libraries offering command line options.
+ * Currently, this API is limited to registering options without argument.
+ *
+ * The register API can be used to resolve circular dependency issues
+ * between EAL and the library. The library uses EAL, but is also initialized
+ * by EAL. Hence, EAL depends on the init function of the library. The API
+ * introduced in rte_option allows us to register the library init with EAL
+ * (passing a function pointer) and avoid the circular dependency.
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef int (*rte_option_cb)(void);
+
+/*
+ * Structure describing the EAL command line option being registered.
+ */
+struct rte_option {
+	TAILQ_ENTRY(rte_option) next; /**< Next entry in the list. */
+	char *opt_str;             /**< The option name. */
+	rte_option_cb cb;          /**< Function called when option is used. */
+	int enabled;               /**< Set when the option is used. */
+};
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Register an option to the EAL command line.
+ * When recognized, the associated function will be executed at the end of EAL
+ * initialization.
+ *
+ * The associated structure must be available the whole time this option is
+ * registered (i.e. not stack memory).
+ *
+ * @param opt
+ *  Structure describing the option to parse.
+ */
+void __rte_experimental
+rte_option_register(struct rte_option *opt);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/lib/librte_eal/common/meson.build b/lib/librte_eal/common/meson.build
index 04c4143..2a10d57 100644
--- a/lib/librte_eal/common/meson.build
+++ b/lib/librte_eal/common/meson.build
@@ -34,6 +34,7 @@  common_sources = files(
 	'malloc_mp.c',
 	'rte_keepalive.c',
 	'rte_malloc.c',
+	'rte_option.c',
 	'rte_reciprocal.c',
 	'rte_service.c'
 )
@@ -71,6 +72,7 @@  common_headers = files(
 	'include/rte_malloc_heap.h',
 	'include/rte_memory.h',
 	'include/rte_memzone.h',
+	'include/rte_option.h',
 	'include/rte_pci_dev_feature_defs.h',
 	'include/rte_pci_dev_features.h',
 	'include/rte_per_lcore.h',
diff --git a/lib/librte_eal/common/rte_option.c b/lib/librte_eal/common/rte_option.c
new file mode 100644
index 0000000..02d59a8
--- /dev/null
+++ b/lib/librte_eal/common/rte_option.c
@@ -0,0 +1,54 @@ 
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2018 Intel Corporation.
+ */
+
+#include <unistd.h>
+#include <string.h>
+
+#include <rte_eal.h>
+#include <rte_option.h>
+
+#include "eal_private.h"
+
+TAILQ_HEAD(rte_option_list, rte_option);
+
+struct rte_option_list rte_option_list =
+	TAILQ_HEAD_INITIALIZER(rte_option_list);
+
+static struct rte_option *option;
+
+int
+rte_option_parse(const char *opt)
+{
+	/* Check if the option is registered */
+	TAILQ_FOREACH(option, &rte_option_list, next) {
+		if (strcmp(opt, option->opt_str) == 0) {
+			option->enabled = 1;
+			return 0;
+		}
+	}
+
+	return -1;
+}
+
+void __rte_experimental
+rte_option_register(struct rte_option *opt)
+{
+	TAILQ_FOREACH(option, &rte_option_list, next) {
+		if (strcmp(opt->opt_str, option->opt_str) == 0)
+			RTE_LOG(INFO, EAL, "Option %s has already been registered.",
+					opt->opt_str);
+			return;
+	}
+
+	TAILQ_INSERT_HEAD(&rte_option_list, opt, next);
+}
+
+void
+rte_option_init(void)
+{
+	TAILQ_FOREACH(option, &rte_option_list, next) {
+		if (option->enabled)
+			option->cb();
+	}
+}
diff --git a/lib/librte_eal/linuxapp/eal/Makefile b/lib/librte_eal/linuxapp/eal/Makefile
index 7280885..51deb57 100644
--- a/lib/librte_eal/linuxapp/eal/Makefile
+++ b/lib/librte_eal/linuxapp/eal/Makefile
@@ -75,6 +75,7 @@  SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += malloc_elem.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += malloc_heap.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += malloc_mp.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += rte_keepalive.c
+SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += rte_option.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += rte_service.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += rte_reciprocal.c
 
diff --git a/lib/librte_eal/linuxapp/eal/eal.c b/lib/librte_eal/linuxapp/eal/eal.c
index a00cebf..70ab032 100644
--- a/lib/librte_eal/linuxapp/eal/eal.c
+++ b/lib/librte_eal/linuxapp/eal/eal.c
@@ -48,6 +48,7 @@ 
 #include <rte_atomic.h>
 #include <malloc_heap.h>
 #include <rte_vfio.h>
+#include <rte_option.h>
 
 #include "eal_private.h"
 #include "eal_thread.h"
@@ -600,12 +601,20 @@  eal_parse_args(int argc, char **argv)
 
 	argvopt = argv;
 	optind = 1;
+	opterr = 0;
 
 	while ((opt = getopt_long(argc, argvopt, eal_short_options,
 				  eal_long_options, &option_index)) != EOF) {
 
-		/* getopt is not happy, stop right now */
+		/*
+		 * getopt didn't recognise the option, lets parse the
+		 * registered options to see if the flag is valid
+		 */
 		if (opt == '?') {
+			ret = rte_option_parse(argv[optind-1]);
+			if (ret == 0)
+				continue;
+
 			eal_usage(prgname);
 			ret = -1;
 			goto out;
@@ -1080,6 +1089,9 @@  rte_eal_init(int argc, char **argv)
 
 	rte_eal_mcfg_complete();
 
+	/* Call each registered callback, if enabled */
+	rte_option_init();
+
 	return fctret;
 }
 
diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
index 08e3bc2..12ace18 100644
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map
@@ -351,6 +351,7 @@  EXPERIMENTAL {
 	rte_mp_request_sync;
 	rte_mp_request_async;
 	rte_mp_sendmsg;
+	rte_option_register;
 	rte_service_lcore_attr_get;
 	rte_service_lcore_attr_reset_all;
 	rte_service_may_be_active;