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

build/linux/sysroot_scripts/install-sysroot.py

Index: build/linux/sysroot_scripts/install-sysroot.py
diff --git a/build/linux/sysroot_scripts/install-sysroot.py b/build/linux/sysroot_scripts/install-sysroot.py
index c1112891e282c0b255925f97cf6dfbbe63c1d562..bd6e1e38512060d53aab722b22715eed885d1ad8 100755
--- a/build/linux/sysroot_scripts/install-sysroot.py
+++ b/build/linux/sysroot_scripts/install-sysroot.py
@@ -132,6 +132,17 @@ def main():
   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.