Triple boot on MBP 2019 (T2)
You need to use the bcdboot
command to create the boot files for each Windows installation in separate EFI partitions.
Note: This answer assume Bitlocker has be disabled. In other words, the answer assumes the Windows NTFS partitions are not encrypted.
Below is an example which closely (but not exactly) matches your situation.
Here, I have already setup two Windows 10 installations where the boot manager, shown below, is used to choose which Windows to boot.
The drive, used in this example, contains your 1st, 2nd, 3rd, 7th, 8th and 11th partitions, albeit the sizes might be different. Also, note the following:
- My equivalent to your 3rd partition has the label
BOOTCAMP
. - My equivalent to your 7th partition is a unformatted and of type
Microsoft Basic Data
.
For simplicity, I did not include separate recovery partitions. However, creating these partitions for both Windows installations is possible. If using the Boot Camp Assistant to create the first Windows installation, then you probably will need to create and initialize the recovery partition after Windows finishes installing.
Note: A good new question would be how to create the second Windows installation without making such a mess of the partitioning.
Here I will assume you correctly built the Windows USB installer.
Below is the procedure I used to separate the booting of the two Windows installations.
Boot from the Windows 10 USB installer. Proceed until you reach the screen shown below.
At this point, any drivers that may be required to access
disk0
have been loaded.
Next, enter the shift+F10 key combination to open a Command Prompt window, as shown below.
Next, use the diskpart
, ren
and bcdboot
commands to separate the booting of the two Windows installations. Below is an example of how I accomplished this. Most of the work involves creating the second EFI partition.
Microsoft Windows [Version 10.0.18362.418]
(c) 2019 Microsoft Corporation. All rights reserved.
X:\Sources>diskpart
Microsoft DiskPart version 10.0.18362.1
Copyright (C) Microsoft Corporation.
On computer: MINWINPC
DISKPART> select disk 0
Disk 0 is now the selected disk.
DISKPART> list partition
Partition ### Type Size Offset
------------- ---------------- ------- -------
Partition 1 System 315 MB 1024 KB
Partition 2 Unknown 722 GB 316 MB
Partition 3 Primary 208 GB 722 GB
Partition 4 Primary 315 MB 931 GB
Partition 5 Reserved 16 MB 931 GB
Partition 6 Primary 68 GB 931 GB
DISKPART> list volume
Volume ### Ltr Label Fs Type Size Status Info
---------- --- ----------- ----- ---------- ------- --------- --------
Volume 0 E WinInstall exFAT Removable 14 GB Healthy
Volume 1 C BOOTCAMP NTFS Partition 208 GB Healthy
Volume 2 RAW Partition 315 MB Healthy
Volume 3 D Loisir NTFS Partition 68 GB Healthy
Volume 4 EFI FAT32 Partition 315 MB Healthy Hidden
DISKPART> select volume 4
Volume 4 is the selected volume.
DISKPART> assign letter=s
DiskPart successfully assigned the drive letter or mount point.
DISKPART> select volume 2
Volume 2 is the selected volume.
DISKPART> format fs=fat32 label=EFI2 quick
100 percent completed
DiskPart successfully formatted the volume.
DISKPART> set id=c12a7328-f81f-11d2-ba4b-00a0c93ec93b
DiskPart successfully set the partition ID.
DISKPART> gpt attributes=0x0000000000000000
DiskPart successfully assigned the attributes to the selected GPT partition.
DISKPART> assign letter=t
DiskPart successfully assigned the drive letter or mount point.
DISKPART> detail partition
Partition 4
Type : c12a7328-f81f-11d2-ba4b-00a0c93ec93b
Hidden : Yes
Required: No
Attrib : 0000000000000000
Offset in Bytes: 1000340455424
Volume ### Ltr Label Fs Type Size Status Info
---------- --- ----------- ----- ---------- ------- --------- --------
* Volume 2 T EFI2 FAT32 Partition 315 MB Healthy Hidden
DISKPART> list partition
Partition ### Type Size Offset
------------- ---------------- ------- -------
Partition 1 System 315 MB 1024 KB
Partition 2 Unknown 722 GB 316 MB
Partition 3 Primary 208 GB 722 GB
* Partition 4 System 315 MB 931 GB
Partition 5 Reserved 16 MB 931 GB
Partition 6 Primary 68 GB 931 GB
DISKPART> list volume
Volume ### Ltr Label Fs Type Size Status Info
---------- --- ----------- ----- ---------- ------- --------- --------
Volume 0 E WinInstall exFAT Removable 14 GB Healthy
Volume 1 C BOOTCAMP NTFS Partition 208 GB Healthy
* Volume 2 T EFI2 FAT32 Partition 315 MB Healthy Hidden
Volume 3 D Loisir NTFS Partition 68 GB Healthy
Volume 4 S EFI FAT32 Partition 315 MB Healthy Hidden
DISKPART> exit
Leaving DiskPart...
X:\Sources>ren s:\efi\microsoft\boot\bcd BCD.original
X:\Sources>bcdboot c:\windows /s s:
Boot files successfully created.
X:\Sources>bcdboot d:\windows /s t:
Boot files successfully created.
X:\Sources>exit
After the Command Prompt window closes, you can abort the Windows installation.
References
UEFI/GPT-based hard drive partitions
DiskPart commands
ren
BCDBoot Command-Line Options