[v9,09/14] build: optional NUMA and cpu counts detection

diff --git a/buildtools/get_cpu_count.py b/buildtools/get_cpu_count.py
new file mode 100644
index 000000000..b269d557b
--- /dev/null
+++ b/buildtools/get_cpu_count.py
@@ -0,0 +1,7 @@ 
+#!/usr/bin/env python3
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright (c) 2020 PANTHEON.tech s.r.o.
+
+import os
+
+print(os.cpu_count())
diff --git a/buildtools/get_numa_count.py b/buildtools/get_numa_count.py
new file mode 100644
index 000000000..be73c5c3f
--- /dev/null
+++ b/buildtools/get_numa_count.py
@@ -0,0 +1,22 @@ 
+#!/usr/bin/env python3
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright (c) 2020 PANTHEON.tech s.r.o.
+
+import ctypes
+import glob
+import os
+import subprocess
+
+if os.name == 'posix':
+    if os.path.isdir('/sys/devices/system/node'):
+        print(len(glob.glob('/sys/devices/system/node/node*')))
+    else:
+        subprocess.run(['sysctl', '-n', 'vm.ndomains'])
+
+elif os.name == 'nt':
+    libkernel32 = ctypes.windll.kernel32
+
+    count = ctypes.c_ulong()
+
+    libkernel32.GetNumaHighestNodeNumber(ctypes.pointer(count))
+    print(count.value + 1)
diff --git a/buildtools/meson.build b/buildtools/meson.build
index 04808dabc..925e733b1 100644
--- a/buildtools/meson.build
+++ b/buildtools/meson.build
@@ -17,3 +17,5 @@  else
 endif
 map_to_win_cmd = py3 + files('map_to_win.py')
 sphinx_wrapper = py3 + files('call-sphinx-build.py')
+get_cpu_count_cmd = py3 + files('get_cpu_count.py')
+get_numa_count_cmd = py3 + files('get_numa_count.py')
diff --git a/config/meson.build b/config/meson.build
index c7f7aa6e2..ce0abe49b 100644
--- a/config/meson.build
+++ b/config/meson.build
@@ -231,8 +231,6 @@  foreach arg: warning_flags
 endforeach
 
 # set other values pulled from the build options
-dpdk_conf.set('RTE_MAX_LCORE', get_option('max_lcores'))
-dpdk_conf.set('RTE_MAX_NUMA_NODES', get_option('max_numa_nodes'))
 dpdk_conf.set('RTE_MAX_ETHPORTS', get_option('max_ethports'))
 dpdk_conf.set('RTE_LIBEAL_USE_HPET', get_option('use_hpet'))
 dpdk_conf.set('RTE_ENABLE_TRACE_FP', get_option('enable_trace_fp'))
@@ -251,6 +249,51 @@  compile_time_cpuflags = []
 subdir(arch_subdir)
 dpdk_conf.set('RTE_COMPILE_TIME_CPUFLAGS', ','.join(compile_time_cpuflags))
 
+max_lcores = get_option('max_lcores')
+if max_lcores > 0
+	# Overwrite the default value from arch_subdir with user input
+	dpdk_conf.set('RTE_MAX_LCORE', max_lcores)
+elif max_lcores == -1
+	# Overwrite the default value with discovered values
+	if meson.is_cross_build()
+		error('Discovery of max_lcores is not supported for cross-compilation.')
+	endif
+	# Discovery makes sense only for non-cross builds
+	max_lcores = run_command(get_cpu_count_cmd).stdout().to_int()
+	min_lcores = 2
+	# DPDK must be build for at least 2 cores
+	if max_lcores < min_lcores
+		message('Found less than @0@ cores, building for @0@ cores'.format(min_lcores))
+		max_lcores = min_lcores
+	else
+		message('Found @0@ cores'.format(max_lcores))
+	endif
+	dpdk_conf.set('RTE_MAX_LCORE', max_lcores)
+endif
+
+max_numa_nodes = get_option('max_numa_nodes')
+if max_numa_nodes > 0
+	# Overwrite the default value from arch_subdir with user input
+	dpdk_conf.set('RTE_MAX_NUMA_NODES', max_numa_nodes)
+elif max_numa_nodes == -1
+	# Overwrite the default value with discovered values
+	if meson.is_cross_build()
+		error('Discovery of max_numa_nodes not supported for cross-compilation.')
+	endif
+	# Discovery makes sense only for non-cross builds
+	max_numa_nodes = run_command(get_numa_count_cmd).stdout().to_int()
+	message('Found @0@ numa nodes'.format(max_numa_nodes))
+	dpdk_conf.set('RTE_MAX_NUMA_NODES', max_numa_nodes)
+endif
+
+# check that cpu and numa count is set and error out if it's not set
+if not dpdk_conf.has('RTE_MAX_LCORE')
+	error('Number of cores not specified.')
+endif
+if not dpdk_conf.has('RTE_MAX_NUMA_NODES')
+	error('Number of numa nodes not specified.')
+endif
+
 # set the install path for the drivers
 dpdk_conf.set_quoted('RTE_EAL_PMD_PATH', eal_pmd_path)
 
diff --git a/config/x86/meson.build b/config/x86/meson.build
index 31bfa63b1..4989d47f3 100644
--- a/config/x86/meson.build
+++ b/config/x86/meson.build
@@ -57,3 +57,5 @@  else
 endif
 
 dpdk_conf.set('RTE_CACHE_LINE_SIZE', 64)
+dpdk_conf.set('RTE_MAX_LCORE', 128)
+dpdk_conf.set('RTE_MAX_NUMA_NODES', 4)
diff --git a/meson_options.txt b/meson_options.txt
index bc649f245..0c9adb1bb 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -26,10 +26,10 @@  option('machine', type: 'string', value: 'native',
 	description: 'set the target machine type. Set to generic for a build usable on all machines of the build machine architecture, set to native to let the compiler pick the architecture of the build machine.')
 option('max_ethports', type: 'integer', value: 32,
 	description: 'maximum number of Ethernet devices')
-option('max_lcores', type: 'integer', value: 128,
-	description: 'maximum number of cores/threads supported by EAL')
-option('max_numa_nodes', type: 'integer', value: 4,
-	description: 'maximum number of NUMA nodes supported by EAL')
+option('max_lcores', type: 'integer', value: 0,
+	description: 'maximum number of cores/threads supported by EAL. Set to positive integer to overwrite per-arch or cross-compilation defaults. Set to -1 to detect the number of cores on the build machine.')
+option('max_numa_nodes', type: 'integer', value: 0,
+	description: 'maximum number of NUMA nodes supported by EAL. Set to positive integer to overwrite per-arch or cross-compilation defaults. Set to -1 to detect the number of numa nodes on the build machine.')
 option('enable_trace_fp', type: 'boolean', value: false,
 	description: 'enable fast path trace points.')
 option('tests', type: 'boolean', value: true,