Reserving large contiguous block of RAM for device

[Jacques Fourie]

Hi,

I am in the process of porting a Linux device driver to FreeBSD. In Linux, a
large block of RAM (256MB) is reserved by using the 'mem=' and 'memmap='
arguments to the kernel. In the device driver, ioremap() is used to map this
memory into kernel virtual memory. In FreeBSD contigmalloc() is available
but due to the large amount of physical memory required this may not work
reliably. Is there an existing method to reserve a large block of RAM early
in the boot process?

regards,
jacques