Troubleshooting EFI boot problem

[Paul Thornton]

Hi Folks,

I've been trying to install the stock UEFI memstick of 10.2 RELEASE on 
an Acer V5-122P laptop.

Its UEFI BIOS seems to work ok (it installs and boots Windows 10 fine).

When I choose the USB drive from the boot menu to start the install, I 
get no further than the loader.  All I see on screen is:

 >> FreeBSD EFI boot block
       Loader path: /boot/loader.efi
panic: Load failed

Putting the memstick into another machine, everything looks like it is 
in the correct place:

# gpart show /dev/da8
=>       3  15663099  da8  GPT  (7.5G)
          3      1600    1  efi  (800K)
       1603        32    2  freebsd-boot  (16K)
       1635   1511040    3  freebsd-ufs  (738M)
    1512675      2048    4  freebsd-swap  (1.0M)
    1514723  14148379       - free -  (6.7G)

# mount /dev/da8p3 /mnt
# ls -al /mnt/boot/loader.efi
-r-xr-xr-x  1 root  wheel  337363 Aug 12 15:44 /mnt/boot/loader.efi
# umount /mnt

# mount -t msdosfs /dev/da8p1 /mnt
# ls -al /mnt/efi/boot/
total 65
drwxr-xr-x  1 root  wheel    512 Apr 26  2014 .
drwxr-xr-x  1 root  wheel    512 Apr 26  2014 ..
-rwxr-xr-x  1 root  wheel  65536 Apr 26  2014 BOOTx64.efi
# umount /mnt

How can I get some more useful information out to start debugging this?

Paul.