How to have Boot Camp and multiple Mac partitions?

[izzy0242mr]

I want to get a Mac (older, like 2011 model, but I'm not sure that matters for this question) running Boot Camp *and* also having a separate partition to boot a different version of Mac OS X.

Any way to do this? Boot Camp doesn't like it when I try to install it on a drive that already has 2 partitions, and I'm worried if I partition the existing Mac OS drive after Boot Camp is installed that it either won't let me or will break something with Boot Camp.

 

[joevt]

Create the Windows partition yourself using Disk Utility.app. Format it as FAT32. Boot the Windows installer. Tell it to erase the partition as NTFS. Install Windows. Install the Boot Camp drivers.
There are instructions in other threads on MacRumors. I think you can use https://github.com/timsutton/brigadier to download Boot Camp drivers?

The Mac model determines if it will boot Windows using legacy BIOS (older) or UEFI (newer/better).

I think the following Mac models can boot using legacy BIOS mode (they have the AppleLegacyLoad app 2B0585EB-D8B8-49A9-8B8C-E21B01AEF2B7 gAppleLegacyLoadAppFileGuid in their firmware):

IM41
IM51
IM52
IM61
IM71
IM91
IM111
IM112
IM121
IM131
IM141
IM142
IM143
IM144
IM151
MB11
MB21
MB31
MB51
MB52
MB71
MBA11
MBA21
MBA31
MBA41
MBA51
MBA61
MBP11
MBP12
MBP21
MBP22
MBP31
MBP51
MBP52
MBP53
MBP55
MBP61
MBP71
MBP81
MBP91
MBP101
MBP102
MBP111
MBP112
MM11
MM31
MM41
MM51
MM61
MM71
MP11
MP21
MP31
MP41
MP51

Some of those you might be able to install using UEFI mode but there could be side effects if you don't boot using the default Boot Camp method for your Mac.

 

[izzy0242mr]

Create the Windows partition yourself using Disk Utility.app. Format it as FAT32. Boot the Windows installer. Tell it to erase the partition as NTFS. Install Windows. Install the Boot Camp drivers.
There are instructions in other threads on MacRumors. I think you can use https://github.com/timsutton/brigadier to download Boot Camp drivers?

The Mac model determines if it will boot Windows using legacy BIOS (older) or UEFI (newer/better).

I think the following Mac models can boot using legacy BIOS mode (they have the AppleLegacyLoad app 2B0585EB-D8B8-49A9-8B8C-E21B01AEF2B7 gAppleLegacyLoadAppFileGuid in their firmware):

IM41
IM51
IM52
IM61
IM71
IM91
IM111
IM112
IM121
IM131
IM141
IM142
IM143
IM144
IM151
MB11
MB21
MB31
MB51
MB52
MB71
MBA11
MBA21
MBA31
MBA41
MBA51
MBA61
MBP11
MBP12
MBP21
MBP22
MBP31
MBP51
MBP52
MBP53
MBP55
MBP61
MBP71
MBP81
MBP91
MBP101
MBP102
MBP111
MBP112
MM11
MM31
MM41
MM51
MM61
MM71
MP11
MP21
MP31
MP41
MP51

Some of those you might be able to install using UEFI mode but there could be side effects if you don't boot using the default Boot Camp method for your Mac.

Thanks, I will try that. I know in the past I've had issues on the MBP7,1 and MBP8,1 models installing Windows without Boot Camp (audio didn't work I think) and it was somehow related to EFI issues that I wasn't able to figure out.

 

[joevt]

If you have a disk with a single Mac OS partition, then you could install Windows to that, then later split the Mac OS partition.

You can use my dumpvols.sh script to capture the partition changes before and after each step, then compare the results to see what's changing. The partition maps will show if the Windows partition should be booted using BIOS or UEFI.

 

[Snowlover]

I did this by installing windows 11 first (by itself), then making a new partition for mac after the windows installation and reinstalling macos from a bootable backup. Then repartition the mac partition to add second macos version etc. This way making changes to the mac side doesn't bork your windows installation.

Before doing this make carbon copy clones of macos, and download the bootcamp drivers for windows. I have never had any luck getting brigadier to work downloading the drivers.

Macs before 2012 will need to have windows installed in legacy bios mode or sound will not work.

I made the windows 11 install usb using Rufus, which can eliminate all the tpm etc restrictions.