dual boot with Linux

[infinityux at yahoo.com]

Hi all I am trying to dual boot my freebsd system with opensuse Linux so I made some changes to appear FreeBSD in grub boot menu. In opensuse I wrote$ sudo -i# nano /etc/grub.d/40_custom     And then,     menuentry "FreeBSD" {set root=(hd0,gpt2)kfreebsd /boot/loader }Now though freebsd is appearing in boot menu but when I am selecting one of them an error message is saying error:invalid signaturePress any key to continue... Can anyone help me? Do I have to install Linux as my first OS and then FreeBSD to appear it in grub menu?