Declaring a specific RAM section as used

I have an embedded system, where the main processor is running linux. A sub processor is running in parallel, and assumes it controls a specific section of RAM. The kernel must still be able to read/write to this section of RAM, but must never allocate it, or use it for anything else.

I'm wondering if there is a simple way to do this.

My understanding (and I haven't tried this, so this is just an outline) is:

1. that you use the 'memmap=nn$ss' parameter to the kernel at boot (nn is size, ss is offset, with optional K/M/G suffixes) to reserve the area of memory that you are using for the dual port to the secondary processor

2. you then create a driver to 'remap_pfn_range' this physical area into user space so that you can access it

Thanks, I'll give that a try.