For building v8 using gn on aix_ppc64, linux_s390x and linux_ppc64.

build/config/ui.gni

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # =============================================
 #   PLEASE DO NOT ADD MORE FLAGS TO THIS FILE
 # =============================================
 #
 # These flags are effectively global. Your feature flag should go near the
 # code it controls. Most of these items are here now because they control
@@ skipping 16 matching lines @@
   # Indicates if Ozone is enabled. Ozone is a low-level library layer for Linux
   # that does not require X11. Enabling this feature disables use of glib, x11,
   # Pango, and Cairo. Default to false on non-Chromecast builds.
   use_ozone = is_chromecast && !is_android
 
   # Indicates if Aura is enabled. Aura is a low-level windowing library, sort
   # of a replacement for GDI or GTK.
   use_aura = is_win || is_linux
 
   # Whether we should use glib, a low level C utility library.
-  use_glib = is_linux
+  use_glib = is_linux && !is_power_or_z

[brettw, 2017/04/26 20:07:42]

As with the is_nacl flag, can you explain why this value affects your V8
compiles?

For this one, why does the CPU architecture affect whether glib is used? I would
expect that to be a function of the OS.

[Dirk Pranke, 2017/04/26 23:32:13]

I think this is because //base has dependencies on glib, and I'd guess that
maybe glib isn't available on their ports?

[rayb, 2017/04/27 19:29:45]

//base does have dependencies on glib. My initial assumption was also that glib
wasn't available on all of our ports. As it certainly wasn't available on the
machines I was testing on. But upon closer inspection, it might just have been
an environment issue, as since then I have managed to get hold of a pLinux 64 BE
machine with the required libraries.

So that makes me almost certain that the required ones(glib-2.0 gmodule-2.0
gobject-2.0 gthread-2.0) do indeed exist on both power and z linux. They are
just not that common, or at least they are uncommon enough for me to not have
them on the machines I was running on. 

Anyways, I will turn them back on for p/Linux and z/Linux. Again, thanks for
catching that.

 }
 
 declare_args() {
   # True means the UI is built using the "views" framework.
   toolkit_views =
       (is_mac || is_win || is_chromeos || use_aura) && !is_chromecast
 }
 
 # Additional dependent variables -----------------------------------------------
 #
@@ skipping 15 matching lines @@
   use_pango = false
 }
 
 # Whether to use atk, the Accessibility ToolKit library
 use_atk = is_desktop_linux && use_x11
 # =============================================
 #   PLEASE DO NOT ADD MORE FLAGS TO THIS FILE
 # =============================================
 #
 # See comment at the top.