Re: [Patch] BaseTools: add some comment for .PrebuildEnv file's usage

["Gao, Liming" <liming.gao@intel.com>]

Reviewed-by: Liming Gao <liming.gao@intel.com>

>-----Original Message-----
>From: Zhu, Yonghong
>Sent: Tuesday, July 25, 2017 1:58 PM
>To: edk2-devel@lists.01.org
>Cc: Gao, Liming <liming.gao@intel.com>
>Subject: [Patch] BaseTools: add some comment for .PrebuildEnv file's usage
>
>This patch add some comments to explain why we use .PrebuildEnv file to
>save environment variable settings set by the prebuild script.
>
>Cc: Liming Gao <liming.gao@intel.com>
>Contributed-under: TianoCore Contribution Agreement 1.0
>Signed-off-by: Yonghong Zhu <yonghong.zhu@intel.com>
>---
> BaseTools/Source/Python/build/build.py | 5 +++++
> 1 file changed, 5 insertions(+)
>
>diff --git a/BaseTools/Source/Python/build/build.py
>b/BaseTools/Source/Python/build/build.py
>index f7634fa..4d05ee2 100644
>--- a/BaseTools/Source/Python/build/build.py
>+++ b/BaseTools/Source/Python/build/build.py
>@@ -1027,10 +1027,15 @@ class Build():
>
>     def LaunchPrebuild(self):
>         if self.Prebuild:
>             EdkLogger.info("\n- Prebuild Start -\n")
>             self.LaunchPrebuildFlag = True
>+            #
>+            # The purpose of .PrebuildEnv file is capture environment variable
>settings set by the prebuild script
>+            # and preserve them for the rest of the main build step, because the
>child process environment will
>+            # evaporate as soon as it exits, we cannot get it in build step.
>+            #
>             PrebuildEnvFile =
>os.path.join(GlobalData.gConfDirectory,'.cache','.PrebuildEnv')
>             if os.path.isfile(PrebuildEnvFile):
>                 os.remove(PrebuildEnvFile)
>             if os.path.isfile(self.PlatformBuildPath):
>                 os.remove(self.PlatformBuildPath)
>--
>2.6.1.windows.1