How to dualboot UEFI the right way?

[David Demelier]

Hi there,

I have a thinkpad X1 carbon that I use with Linux mostly, I'd like to
add a FreeBSD dualboot alongside Linux using grub and UEFI.

My current partition scheme is:

Device             Start       End   Sectors  Size Type
/dev/nvme0n1p1      2048    526335    524288  256M EFI System
/dev/nvme0n1p2    526336   1050623    524288  256M Linux filesystem
/dev/nvme0n1p3   1050624 420481023 419430400  200G Linux filesystem

Is has 40Gb free space to hold FreeBSD.

Once I boot the memstick USB, at installer I used experts mode to
partition and added a partition / as freebsd-ufs. Then the installer
complained that I require a boot partition, I entered yes and it
created a *new* EFI partition, which is obviously wrong.

However, I can't understand how to select the existing EFI partition
and tell bsdinstall to use it (especially which mountpoint?). I've
tried to search some information about that but it looks like not many
people tried that yet.

Has anyone successfully made a dualboot with an existing EFI partition
using bsdinstall? Installing sets manually from the FreeBSD shell may
be an option if required.

Any help is welcomed.

Regards

-- 
David