This command might help you finding out what kernels you have:
$ file /var/www/fog/service/ipxe/bzImage*
/var/www/fog/service/ipxe/bzImage: Linux kernel x86 boot executable bzImage, version 3.15.6 (root@debian64) #1 SMP PREEMPT Fri Jul 18 23:58:44 EDT 2, RO-rootFS, swap_dev 0x5, Normal VGA
/var/www/fog/service/ipxe/bzImage32: Linux kernel x86 boot executable bzImage, version 3.15.6 (root@debian64) #1 SMP PREEMPT Fri Jul 18 23:58:56 EDT 2, RO-rootFS, swap_dev 0x5, Normal VGA
This output is on a 1.2.0 test install on my laptop. So I guess 1.2.0 came with 3.15.6