Use seperate nvlist entries for the romfile and the varfile.
While here, don't leak varfd in bootrom_loadrom().
Reviewed by: jhb, markj
Differential Revision: https://reviews.freebsd.org/D33433
To allow more general use of the bootrom region, separate initialization from
allocation, and allocation from loading a file.
The bootrom segment is the high 16MB of the low 4GB region.
Each allocation in the segment creates a new mapping with specified protection.
By default, allocation begins at the low end of the range. However, the
BOOTROM_ALLOC_TOP flag is provided to locate a provided bootrom in the high
region it is expected to be in.
The existing ROM-file loading code is refactored to use the new interface.
Reviewed by: grehan (earlier version)
Differential Revision: https://reviews.freebsd.org/D24422
devmem is used to represent MMIO devices like the boot ROM or a VESA framebuffer
where doing a trap-and-emulate for every access is impractical. devmem is a
hybrid of system memory (sysmem) and emulated device models.
devmem is mapped in the guest address space via nested page tables similar
to sysmem. However the address range where devmem is mapped may be changed
by the guest at runtime (e.g. by reprogramming a PCI BAR). Also devmem is
usually mapped RO or RW as compared to RWX mappings for sysmem.
Each devmem segment is named (e.g. "bootrom") and this name is used to
create a device node for the devmem segment (e.g. /dev/vmm/testvm.bootrom).
The device node supports mmap(2) and this decouples the host mapping of
devmem from its mapping in the guest address space (which can change).
Reviewed by: tychon
Discussed with: grehan
Differential Revision: https://reviews.freebsd.org/D2762
MFC after: 4 weeks
