bhyve - no memory as declared at bhyveload and bhyve commands

[IPTRACE]

Hello Guys!

I encountered a strange issue.
My VM has got not much memory as I would expect.

bhyvectl --vm=vm1 --destroy
bhyveload -m 8G -c /dev/nmdm1A -d /data/vm1.img vm1
bhyve -c 8 -m 8G -A -H -P -s 0:0,hostbridge -s 1:0,virtio-net,tap1 -s 2:0,virtio-blk,/data/vm1.img -s 31,lpc -l com1,/dev/nmdm1A vm1 &

real memory  = 5368709120 (5120 MB)
avail memory = 4090781696 (3901 MB)

But when I set 2G the valiues are correct.

real memory  = 2147483648 (2048 MB)
avail memory = 2038673408 (1944 MB)

Set 7G and...

real memory  = 8589934592 (8192 MB)
avail memory = 7217377280 (6883 MB)

Set 8G in another VM...

real memory  = 9663676416 (9216 MB)
avail memory = 8258461696 (7875 MB)

Set 16G...

real memory  = 18253611008 (17408 MB)
avail memory = 16586989568 (15818 MB)

I don't know what's going on...
Is this a bug or what?