Mapping Physical Memory without a Device?

[cd_freebsd]

John Baldwin <jhb at FreeBSD.org> wrote:

>> The problem is that the RAM could be used out from under you. You need to reserve it in the VM somehow.  I'm not sure how you would accomplish that.

The areas I said I would map would not be used by the OS for virtual memory pages. BIOS, UMB, Video Frame Buffer all are excluded from use as normal RAM, aren't they? The majority of the time I would be executing the following sequence:

1) Map memory ares.
2) Read memory data. (BIOS VPD, BIOS tables, Video BIOS info, Video info)
3) Unmap memory area.