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
bhyveload: introduce the -c <device> parameter
to select a tty for output (or "stdio")
bhyve: allow the puc and lpc-com backends to
accept a tty in addition to "stdio"
When used in conjunction with the null-modem device,
nmdm(4), this allows attach/detach to the guest console
and multiple concurrent serial ports. kgdb on a serial
port is now functional.
Reviewed by: neel
Requested by: Almost everyone that has used bhyve
MFC after: 10.0
from the command line.
The option syntax is "-e <name=value>". It may be used multiple times to set
multiple environment variables.
Reviewed by: grehan
Requested by: alfred
command line option "-m <memsize in MB>" to specify the memory size.
Prior to this change the user needed to explicitly specify the amount of
memory allocated below 4G (-m <lowmem>) and the amount above 4G (-M <highmem>).
The "-M" option is no longer supported by 'bhyveload' and 'bhyve'.
The start of the PCI hole is fixed at 3GB and cannot be directly changed
using command line options. However it is still possible to change this in
special circumstances via the 'vm_set_lowmem_limit()' API provided by
libvmmapi.
Submitted by: Dinakar Medavaram (initial version)
Reviewed by: grehan
Obtained from: NetApp
