OSX-KVM - March 2021 - Batch Update 1

Changes:

- Upgrade to OpenCore 0.6.7-RELEASE

- Big Sur image building script updates (Nick)
  - See https://github.com/kholia/OSX-KVM/pull/169 for details.

- Removed history to reduce repository size

scripts/create_dmg_highsierra.sh

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+# Create a "ISO" (DMG) image for powering offline macOS installations
+
+# Bail at first ISO creation error
+set -e
+
+display_help() {
+    echo "Usage: $(basename $0) [-h] [<path/to/install_app.app> <path/to/output_iso_file.iso>]"
+    exit 0
+}
+
+if [ "$1" == "-h" ] ; then
+    display_help
+fi
+
+if [ "$#" -eq 2 ]
+then
+    in_path=$1
+    dmg_path=$2
+elif [ "$#" -eq 0 ]
+then
+    in_path=/Applications/Install\ macOS\ High\ Sierra.app
+    dmg_path=~/Desktop/HighSierra.dmg
+    echo "Using default paths:"
+    echo "Install app: $in_path"
+    echo "Output disk: $dmg_path"
+else
+    display_help
+fi
+
+# Borrrowed from multiple internet sources
+hdiutil create -o "$dmg_path" -size 5600m -layout GPTSPUD -fs HFS+J
+hdiutil attach "$dmg_path" -noverify -mountpoint /Volumes/install_build
+sudo "$in_path/Contents/Resources/createinstallmedia" --volume /Volumes/install_build --nointeraction
+
+# createinstallmedia may leave a bunch of subvolumes still mounted when it exits, so we need to use -force here.
+hdiutil detach -force "/Volumes/Install macOS High Sierra"