Can we update the $arch for aarch64 to have capability to choose arm64? #71

Currently, $arch for aarch64 is set as "armv7l".

https://github.com/hokaccha/nodebrew/blob/master/nodebrew

    } elsif ($machine =~ m/aarch64/) {
        $arch = 'armv7l';

Since "armv7l" is 32-bit, can we change it to be able to select "arm64" (64-bit) as well?

The armv7l binaries provided by Node.js are 32-bit binary while aarch64 is a 64-bit archtecture.

$ file node-v11.2.0-linux-armv7l/bin/node 
node-v11.2.0-linux-armv7l/bin/node: ELF 32-bit LSB executable, ARM, EABI5 version 1 (GNU/Linux), dynamically linked, interpreter /lib/ld-linux-armhf.so.3, for GNU/Linux 3.16.42, not stripped

This is because the original pull-request is made for Chrome OS where the OS is 64-bit but the userland is 32-bit for some efficiency.

Below is the original pull-request to add an aarch64 configuration to the Nodebrew.

PR : #69
Merge : 5117ab1

And it seems that the request came from the following issue of Chromebrew for your reference.

chromebrew/chromebrew#2405

Since aarch64 is a 64-bit architecture, it would be nice if we can choose "arm64" along with "armv7l" as well.
Node.js offers arm64 64-bit binaries which are native to aarch64.

$ file node-v11.2.0-linux-arm64/bin/node 
node-v11.2.0-linux-arm64/bin/node: ELF 64-bit LSB executable, ARM aarch64, version 1 (GNU/Linux), dynamically linked, interpreter /lib/ld-linux-aarch64.so.1, for GNU/Linux 3.7.0, BuildID[sha1]=327b8840de15505d13a9dc1ca8cfa3662ca6eb5b, not stripped

I need this to use Nodebrew on aarch64 systems where the userland is also 64-bit such as Debian 9 on Gemini PDA.
It may be the case for Raspberry Pi 64-bit OS as well.

Here's a patch to resolve it.

It uses ptrsize to check the bitness of the userland binary by picking up the perl itself as a sample.

I have tested it on a Debian 9 aarch64 system.
It downloads and installs the 64-bit binary with no problem.

I have not tested it for Chrome OS since I do not have one.
I hope it works well on the Chrome OS.

diff --git a/nodebrew b/nodebrew
index 9f6da59..0273107 100755
--- a/nodebrew
+++ b/nodebrew
@@ -733,7 +733,12 @@ sub system_info {
     } elsif ($machine =~ m/armv7l/) {
         $arch = 'armv7l';
     } elsif ($machine =~ m/aarch64/) {
-        $arch = 'armv7l';
+        use Config;
+        if($Config{ptrsize} == 8) {
+          $arch = 'arm64';
+        } else {
+          $arch = 'armv7l';
+        }
     } elsif ($sysname =~ m/sunos/i) {
         # SunOS $machine => 'i86pc'. but use 64bit kernel.
         # Solaris 11 not support 32bit kernel.