memmap in FreeBSD

[mangesh chitnis]

Hi,

What is the memmap equivalent of Linux in FreeBSD?

In Linux memmap is used to reserve a portion of physical memory. This is used as a kernel boot argument. E.g.: memmap=2G$1G will reserve 1GB memory above 2GB,  incase I have 3GB RAM. This 1GB reserved memory is not visible to the OS, however this 1GB can be used using ioremap. 
How can I reserve memory in FreeBSD and later use it i.e memmap and ioremap equivalent?

I have tried using hw.physmem loader parameter.
I have 3 GB system memory and I have set hw.physmem=2G. 


sysctl -a shows:
hw.physmem: 2.12G

hw.usermem: 1.9G
hw.realmem: 2.15G

devinfo -rv shows:
ram0: 

0x00-0x9f3ff 
0x10000000-0xbfedffff 
0xbff00000-0xbfffffff

Here, looks like it is showing the full 3 GB mapping.
Now, how do I know which is that 1 GB available memory (In Linux, this memory is shown as reserved in /proc/iomem under System RAM) ? Also, which function(similar to ioremap) should I call to map the physical address to virtual address?


Thanks.