Install macOS X on Mac Pro

Short instructions on how to install macOS X Lion onto a 2010 Mac Pro using the official .dmg file from Apple. It would be nice to install Mountain Lion but for some reason that dmg is not available from the support website.

Prereq

• macOS X Lion Installer dmg: Available from Apple
• Alpine Linux
• XAR Source Code
• 6GiB or greater USB Drive

Step 1: Compile XAR

XAR in the Alpine repo will not extract the files from the .pkg so the source must be compiled manually.

Source code for XAR from Github

Besides build-base xar requires:

apk add openssl-dev musl-fts-dev

Generate the configure script:

autoreconf -i
./configure

This step will fail, the configure.ac file requires that the OpenSSL check be modified to work on a modern system (line 327):

dnl
dnl Configure libcrypto (part of OpenSSL).
dnl
have_libcrypto="1"

Run configure again and make:

./configure
make

The last step will fail... no problem just do it again and include the missing libraries at the end of the compile command:

gcc -Wall -g -O2  -o src/xar src/xar.o -Wl,-rpath,/home/user/Downloads/tmp/xar-master/xar/lib -Llib  lib/libxar.a -llzma -lbz2 -lz  -lxml2 -L/lib -lz -llzma -lm -lcrypto -lssl -lfts

Check it works by running the help command:

src/xar --help

Step 2: Extract the xar pkg file from the dmg

7z x InstallMacOSX.dmg

Step 3: Extract the dmg from the pkg

Find where the InstallMacOSX.pkg file is and extract it:

mkdir tmp
cd tmp
src/xar -t -f InstallMacOSX.pkg

Step 4: Use dmg2img to write the install dmg

Find the InstallESD.dmg file and alter the command below to taste (/dev/sdc is the USB drive)

dmg2img -v -i InstallESD.dmg -o /dev/sdc

Step 4: Boot from USB

Press Alt (or Option) whilst booting the machine to show the UEFI boot menu.