Creating a MacOS Bootable IOS Image

When you need to install MacOS on a virtual machine instead of the hardware you will need a bootable image. These steps are quick and basic steps compiled from multiple web sites on creating the image.

MacOS 10.15 Catalina

Download the macOS Catalina install app from the Mac App store into your Applications folder. It should be named “Install macOS Catalina.app”.

Next create an empty HFS file system DMG files /tmp with the terminal command:

hdiutil create -o /tmp/Catalina -size 8500m -volname Catalina -layout SPUD -fs HFS+J

Now mount the empty file system with the terminal command:

hdiutil attach /tmp/Catalina.dmg -noverify -mountpoint /Volumes/Catalina

Now use the Install macOS Catalina createinstallmedia terminal command on the empty file system to build an installer:

sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/Catalina --nointeraction

This step will take a few minutes and should first erase the empty image, then copy the necessary install image files over to it. You will notice the image is renamed to “Install macOS Catalina” during the process. Once it is complete you should umount the image with the terminal command:

hdiutil detach /volumes/Install\ macOS\ Catalina

Finally convert the DMG file into an ISO image with the terminal commands:

hdiutil convert /tmp/Catalina.dmg -format UDTO -o ~/Desktop/Catalina.cdr
mv ~/Desktop/Catalina.cdr ~/Desktop/Catalina.iso

Finally cleanup the temporary file with the terminal command:

rm /tmp/Catalina.dmg

The produced ISO file should work to install MacOS on VMware running on Apple hardware. I have tested with VMware ESXi running on a MacPro (black trashcan model) without issue.

MacOS 11.0 Big Sur

Download the macOS Big Sur install app from the Mac App store into your Applications folder. It should be named “Install macOS Big Sur.app”.

Next create an empty HFS file system DMG files /tmp with the terminal command:

hdiutil create -o /tmp/BigSur -size 16000m -volname BigSur -layout SPUD -fs HFS+J

Now mount the empty file system with the terminal command:

hdiutil attach /tmp/BigSur.dmg -noverify -mountpoint /Volumes/BigSur

Now use the Install macOS Big Sur createinstallmedia terminal command on the empty file system to build an installer:

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/BigSur --nointeraction

This step will take a few minutes and should first erase the empty image, then copy the necessary install image files over to it. You will notice the image is renamed to “Install macOS Big Sur” during the process. Once it is complete you should umount the image with the terminal command:

hdiutil detach /volumes/Install\ macOS\ Big\ Sur

Finally convert the DMG file into an ISO image with the terminal commands:

hdiutil convert /tmp/BigSur.dmg -format UDTO -o ~/Desktop/BigSur.cdr
mv ~/Desktop/BigSur.cdr ~/Desktop/BigSur.iso

Finally cleanup the temporary file with the terminal command:

rm /tmp/BigSur.dmg

The produced ISO file should work to install MacOS on VMware running on Apple hardware. I have tested with VMware ESXi running on a MacPro (black trashcan model). ESXi 6.7u3 or later is the required version and you must add the following to the VM configuration:

smbios.reflectHost = "TRUE"

MacOS 12.0 Monterey

Download the macOS Monterey install app from the Mac App store into your Applications folder. It should be named “Install macOS Monterey.app”.

Next create an empty HFS file system DMG files /tmp with the terminal command:

hdiutil create -o /tmp/Monterey -size 16000m -volname Monterey -layout SPUD -fs HFS+J

Now mount the empty file system with the terminal command:

hdiutil attach /tmp/Monterey.dmg -noverify -mountpoint /Volumes/Monterey

Now use the Install macOS Monterey createinstallmedia terminal command on the empty file system to build an installer:

sudo /Applications/Install\ macOS\ Monterey.app/Contents/Resources/createinstallmedia --volume /Volumes/Monterey --nointeraction

This step will take a few minutes and should first erase the empty image, then copy the necessary install image files over to it. You will notice the image is renamed to “Install macOS Monterey” during the process. Once it is complete you should umount the image with the terminal command:

hdiutil detach /volumes/Install\ macOS\ Monterey

Finally convert the DMG file into an ISO image with the terminal commands:

hdiutil convert /tmp/Monterey.dmg -format UDTO -o ~/Desktop/Monterey.cdr
mv ~/Desktop/Monterey.cdr ~/Desktop/Monterey.iso

Finally cleanup the temporary file with the terminal command:

rm /tmp/Monterey.dmg

The produced ISO file should work to install MacOS on VMware running on Apple hardware. I have tested with VMware ESXi running on a MacPro (black trashcan model). ESXi 6.7u3 or later is the required version and you must add the following to the VM configuration:

smbios.reflectHost = "TRUE"