Install both 32 and 64 bit x86 sysroots when arm is the target_cpu

build/linux/sysroot_scripts/install-sysroot.py

 #!/usr/bin/env python
 # Copyright (c) 2013 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.
 
 # Script to install a Debian Wheezy sysroot for making official Google Chrome
 # Linux builds.
 # The sysroot is needed to make Chrome work for Debian Wheezy.
 # This script can be run manually but is more often run as part of gclient
 # hooks. When run from hooks this script should be a no-op on non-linux
@@ skipping 114 matching lines @@
     target_arch = options.arch
   else:
     target_arch = DetectArch(gyp_defines)
     if not target_arch:
       print 'Unable to detect host architecture'
       return 1
 
   if options.running_as_hook and not UsingSysroot(target_arch, gyp_defines):
     return 0
 
+  # Android requires both 32 and 64 bit sysroots (for v8 snapshots).
+  if target_arch == 'amd64':

[Dirk Pranke, 2015/11/05 22:49:38]

I'm confused. I thought we established that you need both 32-bit and 64-bit x86
sysroots for *32-bit arm* target_arch builds? 

Shouldn't this be:

    if target_arch == 'arm':
      ret = _InstallSysroot('amd64')
      if ret:
        return ret
      ret = _InstallSysroot('i386')
      if ret:
        return ret

    return _InstallSysroot(target_arch)

?

[agrieve, 2015/11/06 03:25:22]

Ah, okay, the build instructions I was following didn't include setting
target_cpu directly, and the script doesn't have a "if OS=android, then
target_arch = arm", which is what GYP / GN do.

So... you're right that is would have done the wrong thing if target_arch was
explicitly set.

I've changed it now to look for OS=android, and also consult chromium.gyp_env
(which is where all of our build instructions assume you set OS=android).
Verified you need only arm64 for 64 bit builds, and x86 for 32 bit builds. You
don't actually need both.

+    ret = _InstallSysroot(target_arch)
+    if ret:
+      return ret
+    target_arch = 'i386'
+
+  return _InstallSysroot(target_arch)
+
+
+def _InstallSysroot(target_arch):
   # The sysroot directory should match the one specified in build/common.gypi.
   # TODO(thestig) Consider putting this else where to avoid having to recreate
   # it on every build.
   linux_dir = os.path.dirname(SCRIPT_DIR)
   if target_arch == 'amd64':
     sysroot = os.path.join(linux_dir, SYSROOT_DIR_AMD64)
     tarball_filename = TARBALL_AMD64
     tarball_sha1sum = TARBALL_AMD64_SHA1SUM
     revision = REVISION_AMD64
   elif target_arch == 'arm':
@@ skipping 51 matching lines @@
   parser = optparse.OptionParser('usage: %prog [OPTIONS]')
   parser.add_option('--running-as-hook', action='store_true',
                     default=False, help='Used when running from gclient hooks.'
                                         ' In this mode the sysroot will only '
                                         'be installed for official Linux '
                                         'builds or ARM Linux builds')
   parser.add_option('--arch', type='choice', choices=valid_archs,
                     help='Sysroot architecture: %s' % ', '.join(valid_archs))
   options, _ = parser.parse_args()
   sys.exit(main())