/boot/loader can't load kernel if too many pool/devices

Hello,

During my tests (succesful) to directly boot from ZFS (with zfsboot and 
gptzfsboot) I encounter the error "can't boot 'kernel'" if too many 
devices/pools are connected to the machine. In my case:

2 SAS disks with 2 pools
2 SATA disks with 2 pools
1 USB key with one pool

`heap` command:

Active Allocations: 171/173
536576 bytes reserved 527800 bytes allocated

`ls` command:

open '/' failed: too many open files

If I reboot without the USB key all is OK.

If I reboot from the USB key after disconnecting 2 disks all is OK.

By the way, the /boot/loader in 7.2-STABLE don't work, complains about 
forth not found.

The previous tests were made with 7.2-STABLE (May 31) with /boot/loader 
from 8.0-CURRENT.

Henri