OvmfPkg: Disable debugging for UNIXGCC to save space

UNIXGCC builds larger images than GCC44, and can have issues
fitting into the FD image. Therefore, when using UNIXGCC,
debug will be disabled by default.

The README file is updated with instructions for selectively
enabling debug for UNIXGCC.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13569 6f19259b-4bc3-4df7-8a09-765794883524
MU SOURCE COMMIT:0b5a5022e5b5377d07d06e6c330fd4305ac47f9d

Platforms/OvmfPkg/OvmfPkgIa32.dsc

@@ -36,6 +36,7 @@
   DEFINE SECURE_BOOT_ENABLE      = FALSE
 
 [BuildOptions]
+  GCC:*_UNIXGCC_*_CC_FLAGS             = -DMDEPKG_NDEBUG
   GCC:RELEASE_*_*_CC_FLAGS             = -DMDEPKG_NDEBUG
   INTEL:RELEASE_*_*_CC_FLAGS           = /D MDEPKG_NDEBUG
   MSFT:RELEASE_*_*_CC_FLAGS            = /D MDEPKG_NDEBUG

Platforms/OvmfPkg/OvmfPkgIa32X64.dsc

@@ -36,6 +36,7 @@
   DEFINE SECURE_BOOT_ENABLE      = FALSE
 
 [BuildOptions]
+  GCC:*_UNIXGCC_*_CC_FLAGS             = -DMDEPKG_NDEBUG
   GCC:RELEASE_*_*_CC_FLAGS             = -DMDEPKG_NDEBUG
   INTEL:RELEASE_*_*_CC_FLAGS           = /D MDEPKG_NDEBUG
   MSFT:RELEASE_*_*_CC_FLAGS            = /D MDEPKG_NDEBUG

Platforms/OvmfPkg/OvmfPkgX64.dsc

@@ -36,6 +36,7 @@
   DEFINE SECURE_BOOT_ENABLE      = FALSE
 
 [BuildOptions]
+  GCC:*_UNIXGCC_*_CC_FLAGS             = -DMDEPKG_NDEBUG
   GCC:RELEASE_*_*_CC_FLAGS             = -DMDEPKG_NDEBUG
   INTEL:RELEASE_*_*_CC_FLAGS           = /D MDEPKG_NDEBUG
   MSFT:RELEASE_*_*_CC_FLAGS            = /D MDEPKG_NDEBUG

Platforms/OvmfPkg/README

@@ -115,3 +115,22 @@ To add network drivers to OVMF:
     -net nic,model=e1000,addr=3 -net nic,model=e1000,addr=4
     -net user,restrict=yes -net user,dhcpstart=10.0.2.10
 
+=== UNIXGCC Debug ===
+
+If you build with the UNIXGCC toolchain, then debugging will be disabled
+due to larger image sizes being produced by the UNIXGCC toolchain. The
+first choice recommendation is to use GCC44 or newer instead.
+
+If you must use UNIXGCC, then you can override the build options for
+particular libraries and modules in the .dsc to re-enable debugging
+selectively. For example:
+  [Components]
+  OvmfPkg/Library/PlatformBdsLib/PlatformBdsLib.inf {
+    <BuildOptions>
+      GCC:*_*_*_CC_FLAGS             = -UMDEPKG_NDEBUG
+  }
+  IntelFrameworkModulePkg/Universal/BdsDxe/BdsDxe.inf {
+    <BuildOptions>
+      GCC:*_*_*_CC_FLAGS             = -UMDEPKG_NDEBUG
+  }
+