From 7e4024be9740c68021297d6feb2de33b31d0acf8 Mon Sep 17 00:00:00 2001
From: Oliver Smith <ollieparanoid@bitmessage.ch>
Date: Wed, 26 Jul 2017 19:01:44 +0000
Subject: [PATCH] Fix #260, fix #87: Don't cross-compile when not necessary
 (#265)

---
 pmb/build/autodetect.py |  3 ++-
 pmb/chroot/init.py      | 10 ++++++----
 pmb/chroot/shutdown.py  |  9 ++++++---
 pmb/parse/arch.py       | 18 ++++++++++++++++++
 4 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/pmb/build/autodetect.py b/pmb/build/autodetect.py
index 89fc8c98..51e6d1e2 100644
--- a/pmb/build/autodetect.py
+++ b/pmb/build/autodetect.py
@@ -19,6 +19,7 @@ along with pmbootstrap.  If not, see <http://www.gnu.org/licenses/>.
 import fnmatch
 import pmb.config
 import pmb.chroot.apk
+import pmb.parse.arch
 
 
 def carch(args, apkbuild, carch):
@@ -63,7 +64,7 @@ def crosscompile(args, apkbuild, carch, suffix):
         return None
     if apkbuild["pkgname"].endswith("-repack"):
         return None
-    if carch == args.arch_native:
+    if not pmb.parse.arch.cpu_emulation_required(args, carch):
         return None
     if suffix == "native":
         return "native"
diff --git a/pmb/chroot/init.py b/pmb/chroot/init.py
index 20b2f135..a4f8008a 100644
--- a/pmb/chroot/init.py
+++ b/pmb/chroot/init.py
@@ -45,9 +45,11 @@ def init(args, suffix="native"):
     # When already initialized: just prepare the chroot
     chroot = args.work + "/chroot_" + suffix
     arch = pmb.parse.arch.from_chroot_suffix(args, suffix)
+    emulate = pmb.parse.arch.cpu_emulation_required(args, arch)
+
     pmb.chroot.mount(args, suffix)
     if os.path.islink(chroot + "/bin/sh"):
-        if suffix != "native":
+        if emulate:
             pmb.chroot.binfmt.register(args, arch)
         copy_resolv_conf(args, suffix)
         pmb.chroot.apk.update_repository_list(args, suffix)
@@ -57,7 +59,7 @@ def init(args, suffix="native"):
     pmb.chroot.apk_static.init(args)
 
     # Non-native chroot: require qemu-user-static
-    if suffix != "native":
+    if emulate:
         pmb.chroot.apk.install(args, ["qemu-user-static-repack",
                                       "qemu-user-static-repack-binfmt"])
         pmb.chroot.binfmt.register(args, arch)
@@ -80,7 +82,7 @@ def init(args, suffix="native"):
     # Install alpine-base (no clean exit for non-native chroot!)
     pmb.chroot.apk_static.run(args, ["-U", "--root", chroot,
                                      "--cache-dir", apk_cache, "--initdb", "--arch", arch,
-                                     "add", "alpine-base"], check=(suffix == "native"))
+                                     "add", "alpine-base"], check=(not emulate))
 
     # Create device nodes
     for dev in pmb.config.chroot_device_nodes:
@@ -99,7 +101,7 @@ def init(args, suffix="native"):
                                    " to an eCryptfs folder.)")
 
     # Non-native chroot: install qemu-user-binary, run apk fix
-    if suffix != "native":
+    if emulate:
         arch_debian = pmb.parse.arch.alpine_to_debian(arch)
         pmb.helpers.run.root(args, ["cp", args.work +
                                     "/chroot_native/usr/bin/qemu-" + arch_debian + "-static",
diff --git a/pmb/chroot/shutdown.py b/pmb/chroot/shutdown.py
index f4a685a5..ad4b8ee0 100644
--- a/pmb/chroot/shutdown.py
+++ b/pmb/chroot/shutdown.py
@@ -20,10 +20,11 @@ import logging
 import glob
 import os
 
-import pmb.install.losetup
-import pmb.helpers.mount
 import pmb.chroot
 import pmb.chroot.distccd
+import pmb.helpers.mount
+import pmb.install.losetup
+import pmb.parse.arch
 
 
 def shutdown_cryptsetup_device(args, name):
@@ -73,5 +74,7 @@ def shutdown(args, only_install_related=False):
         # Clean up the rest
         pmb.helpers.mount.umount_all(args, args.work)
         pmb.helpers.mount.umount_all(args, args.work)
-        pmb.chroot.binfmt.unregister(args, args.deviceinfo["arch"])
+        arch = args.deviceinfo["arch"]
+        if pmb.parse.arch.cpu_emulation_required(args, arch):
+            pmb.chroot.binfmt.unregister(args, arch)
         logging.info("Shutdown complete")
diff --git a/pmb/parse/arch.py b/pmb/parse/arch.py
index f5bc81fd..be83947e 100644
--- a/pmb/parse/arch.py
+++ b/pmb/parse/arch.py
@@ -102,3 +102,21 @@ def alpine_to_hostspec(arch):
 
     raise ValueError("Can not map Alpine architecture " + arch +
                      " to the right hostspec value")
+
+
+def cpu_emulation_required(args, arch):
+    # Obvious case: host arch is target arch
+    if args.arch_native == arch:
+        return False
+
+    # Other cases: host arch on the left, target archs on the right
+    not_required = {
+        "x86_64": ["x86"],
+        "aarch64": ["armel", "armhf", "armv7"],
+    }
+    if args.arch_native in not_required:
+        if arch in not_required[args.arch_native]:
+            return False
+
+    # No match: then it's required
+    return True