Windows does not start when the virtual machine is allocated 9 or more processors

[ncaq]

I use

• AMD Ryzen Threadripper 1950X 16-Core Processor ← it have 32 thread
• NVMe SSD

% lsblk
NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda           8:0    0   2.7T  0 disk 
├─sda1        8:1    0   199M  0 part /boot
├─sda2        8:2    0     2T  0 part 
│ └─bcache0 253:0    0     2T  0 disk /
└─sda3        8:3    0    20G  0 part [SWAP]
sdb           8:16   0 465.8G  0 disk 
└─sdb1        8:17   0 465.8G  0 part 
sr0          11:0    1  1024M  0 rom  
nvme0n1     259:0    0 953.9G  0 disk 
├─nvme0n1p1 259:1    0   499M  0 part 
├─nvme0n1p2 259:2    0   100M  0 part /boot/efi
├─nvme0n1p3 259:3    0    16M  0 part 
├─nvme0n1p4 259:4    0   683G  0 part 
└─nvme0n1p5 259:5    0 270.3G  0 part 
  └─bcache0 253:0    0     2T  0 disk /

I install Windows to nvme0n1p4. And I usually boot Linux natively.

The problem occurred when I tried booting a different partition of Windows from Linux.

In that case I will execute the following command to make the disk of the virtual machine.

VBoxManage internalcommands createrawvmdk -filename "nvme0n1.vmdk" -rawdisk /dev/nvme0n1

When you enable EFI of the virtual machine, it normally starts up.

However, because it did not move this time, I explored the cause, We discovered that if you allocate more than 9 processors to the virtual machine it will not start. Even at the processor bar, 16 is assigned to the safe zone, I did not notice that this was dangerous. I think that it is a natural act that a user of a CPU with 32 threads trying to allocate half 16 threads.

If it is difficult to deal with systematically, In the meantime, I thought that it would be better to warn with 8 or more processors in the red zone.

[Socratis]

Duplicate of at least #17898 if not more.