[PATCH] Platform/Intel: Dynamic NUMBER_OF_PROCESSORS in build.

["Chiu, Chasel" <chasel.chiu@intel.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1913

To improve build performance by default the maximum
processors should be used for building.
To support this, NUMBER_OF_PROCESSORS in build.cfg has
new definition:
  0 = AUTO. Maximum of processors will be used.
  non-zero = limit or force the number of processors.

Test: tried several NUMBER_OF_PROCESSORS settings and
      the build parameter can be updated accordingly
      also builds successfully.

Cc: Michael Kubacki <michael.a.kubacki@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Chasel Chiu <chasel.chiu@intel.com>
---
 Platform/Intel/build.cfg     | 2 +-
 Platform/Intel/build_bios.py | 8 +++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/Platform/Intel/build.cfg b/Platform/Intel/build.cfg
index 6c23e5eabc..fc6e4fe824 100644
--- a/Platform/Intel/build.cfg
+++ b/Platform/Intel/build.cfg
@@ -46,7 +46,7 @@ FSP_TEST_RELEASE = FALSE
 SECURE_BOOT_ENABLE = FALSE
 REBUILD_MODE =
 BUILD_ROM_ONLY =
-NUMBER_OF_PROCESSORS = 1
+NUMBER_OF_PROCESSORS = 0
 
 
 [PLATFORMS]
diff --git a/Platform/Intel/build_bios.py b/Platform/Intel/build_bios.py
index 09eceddeff..864511ac4d 100644
--- a/Platform/Intel/build_bios.py
+++ b/Platform/Intel/build_bios.py
@@ -21,6 +21,7 @@ import shutil
 import argparse
 import traceback
 import subprocess
+import multiprocessing
 from importlib import import_module
 
 try:
@@ -345,7 +346,12 @@ def build(config):
     print(" BUILD_ROM_ONLY = ", config.get("BUILD_ROM_ONLY"))
     print("==========================================")
 
-    command = ["build", "-n", config["NUMBER_OF_PROCESSORS"]]
+    NumberOfProcessors = config["NUMBER_OF_PROCESSORS"]
+    if config["NUMBER_OF_PROCESSORS"] == "0":
+        # 0 means AUTO, maximum number of processors will be set
+        NumberOfProcessors = str(multiprocessing.cpu_count())
+    print ("Number of processors set to " + NumberOfProcessors)
+    command = ["build", "-n", NumberOfProcessors]
 
     if config["REBUILD_MODE"] and config["REBUILD_MODE"] != "":
         command.append(config["REBUILD_MODE"])
-- 
2.13.3.windows.1