My preferred method to boot NVMe on a legacy system though is to boot tianocore UEFI with an NVME module in it[1]. This is a UEFI firmware that you can chainload from a legacy bios. Extremely good compatibility this way, and a great option for any system with an unused usb header.
1: https://winraid.level1techs.com/t/guide-nvme-boot-for-system...
Indeed you can [0]. I have a Supermicro X9DRi-LN4F+ booting from an NVMe drive in a PCIe adapter, works great.
[0]: https://winraid.level1techs.com/t/howto-get-full-nvme-suppor...
Make backups of that USB drive or yeah it would be super cool if you could leverage the bios chip on a motherboard.
This means that the only M.2 drives it’ll boot from are non-NVMe PCIe drives, which were actually made as an HP OEM part (Z Turbo Drive) for this specific model of laptop, but are otherwise nonexistent.
It would be really nice if I could somehow add NVMe support to the laptop’s UEFI, but AFAIK there are no existing solutions for this, other than chainloading from a second drive.
The subsequent model (ZBook G3) actually does support NVMe, but HP never backported that support to the G2/G1 (of course, according to them, if you simply use the specified OEM parts there’s no problem…). Oh well, 2.5” SATA drives work just fine for such an old beast.
If you're interested in going down the rabbit hole, some light googling suggests that HP uses an AMI BIOS. You might be able to mod it: https://winraid.level1techs.com/t/howto-get-full-nvme-suppor...
This is not as rare, there were some drives which are logically seen as a PCI AHCI device (aka SATA controller). It is also possible to directly use actual SATA signaling in M.2 socket. This was way more common, and has a slightly different key position in the connector so it is easy to see visually. However I find it more likely it is a NVMe driver but with the proper option BIOS that makes it bootable.
Contrast this to NVMe drives, which are ubiquitous and cheap.
The laptop unfortunately doesn’t support M.2 SATA, but it does have a regular 2.5” SATA bay, so that’s what I’m using (it still has the OEM drive from the factory :))
If you already have UEFI, but no NVMe support all you need to do is boot into a UEFI shell-script (it’s a thing) which 1. loads a NVMe module (which you’ll need to provide, get it from tianocore), 2. does a device probe and 3. chain boots from the NVMe drive.
It’s not too much work to get going, barely a few megabytes and any old USB stick you have should make do without causing the USB stick to wear out because it won’t have to endure bootloader updates in the booted OS (which may happen if you put your whole /boot on the USB drive).