I'm trying to set up dual/multiboot on an UEFI laptop that came with Windows 8 installed. I'd like to operate with Secure Boot enabled. I can install/configure OS'es with SecureBoot disabled (but I won't operate in CSM mode). I'm OK with blowing out Windows 8, but eventually the laptop will need Windows 8 Pro (x64) installed to support my Windows Phone development gear.
I've read through Microsoft's documentation on UEFI and partitioning at Windows and GPT FAQ. I'm not clear on how many EFI System Partitions (ESP) can be present on a disk. Since the UEFI can authorize access to a particular partition, I think the following holds:
- Microsoft's platform key (PK) is loaded in UEFI
- MS PK allows to access to Microsoft partitions
- MS uses 4 partitions: ESP, MSR, Data, Recovery
- Boot to MS when the Boot Option is selected (enforced by UEFI)
Above, ESP is UEFI System Partition; MSR is Microsoft System Reserved for additional non-preboot files and OEM files; Data is for customary OS files loaded by the loader; and Recovery is just value added OS stuff.
If I add a Linux operating system's platform key to the Platform Key (PK) database, then I believe I would need (at minimum):
- Another ESP partition for booting/loading the Linux OS
- Another Data partition for the customary Linux OS files
The additional ESP would be required because UEFI will need boot/loader files signed under the PK for the particular Boot Option; and UEFI will not allow access to Microsoft's partitions when booting Linux's OS.
How many EFI System Partitions (ESP) can a computer have? Is multi-ESP correct?