[for-4.1,v4,05/12] roms/edk2-funcs.sh: add the qemu_edk2_get_thread_count() function

Commit Message

Laszlo Ersek April 9, 2019, 11 p.m. UTC

The edk2 "build" utility natively supports building modules (that is, INF
files) in parallel. The feature is not useful when building a single
module (with the "-m" option), but it is useful for platform firmware
builds (which include many modules). Add a function that determines the
"-n" option argument for "build", from the MAKEFLAGS variable (i.e. based
on the presence of a make job server).

Signed-off-by: Laszlo Ersek <[e-mail]>
Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>
Tested-by: Philippe Mathieu-Daudé <[e-mail]>
Reviewed-by: Michal Privoznik <[e-mail]>
Reviewed-by: Michael S. Tsirkin <[e-mail]>
Tested-by: Igor Mammedov <[e-mail]>
---

Notes:
    v4:
    
    - no change
    
    v3:
    
    - pick up Igor's T-b
    
    v2:
    
    - pick up Phil's R-b / T-b
    
    - pick up Michal's and Michael's R-b's

 roms/edk2-funcs.sh | 25 ++++++++++++++++++++
 1 file changed, 25 insertions(+)

Patch

diff --git a/roms/edk2-funcs.sh b/roms/edk2-funcs.sh
index d1cb1e4a111e..a9fae7ee891b 100644
--- a/roms/edk2-funcs.sh
+++ b/roms/edk2-funcs.sh
@@ -226,3 +226,28 @@  qemu_edk2_set_cross_env()
 
   eval "export $cross_prefix_var=\$cross_prefix"
 }
+
+
+# Determine the "-n" option argument (that is, the number of modules to build
+# in parallel) for the edk2 "build" utility. Print the result to the standard
+# output.
+#
+# Parameters:
+#   $1: the value of the MAKEFLAGS variable
+qemu_edk2_get_thread_count()
+{
+  local makeflags="$1"
+
+  if [[ "$makeflags" == *--jobserver-auth=* ]] ||
+     [[ "$makeflags" == *--jobserver-fds=* ]]; then
+    # If there is a job server, allow the edk2 "build" utility to parallelize
+    # as many module builds as there are logical CPUs in the system. The "make"
+    # instances forked by "build" are supposed to limit themselves through the
+    # job server. The zero value below causes the edk2 "build" utility to fetch
+    # the logical CPU count with Python's multiprocessing.cpu_count() method.
+    printf '0\n'
+  else
+    # Build a single module at a time.
+    printf '1\n'
+  fi
+}