The following packages are required to build:
- gcc
- flex
- bison
- gmake
Optionally:
- gdb (for debugging)
The configure command line is:
./configure --with-platform=emu CC=gcc LEX=/usr/local/bin/flex \
--enable-grub-mount=no --enable-grub-mkfont=no \
--enable-grub-emu-sdl=no --disable-nls --disable-werror
Running gmake will create a binary, grub-emu, in the grub-core directory.
The command syntax is
grub-emu -r <root-dev> -m <device.map file> [-n] -M <guest-mem> <vmname>
The device.map file is a text file that describes the mappings between grub device names and the filesystem images on the host e.g.
(cd0) /images/centos.iso
(hd1) /images/ubuntu-disk.img
There is an additional device, "(host)", that is always available and allows the host filesystem to be accessed.
The -r parameter takes a device name from the device.map file which will be used as the device for pathnames without a device specifier. Optionally a partition can also be specified, separated by a comma, like "hd0,msdos1". If a grub.cfg file is found on the specified partition it will be loaded automatically.
The -M parameter specifies the amount of bhyve guest memory in MBytes.
The -n parameter disables auto-insertion of "console=ttyS0" to the start of the Linux kernel command-line.
The -S parameter forces wiring of guest memory on FreeBSD-11 hosts. This is required for PCI passthru.
To boot a linux kernel, the 'linux' command is used to load the kernel and specify command-line options, while the 'initrd' command is used to load the initrd. The 'boot' command is then issued to finalize loading, set bhyve register state, and exit grub-emu. grub-emu will auto-insert a "console=ttyS0" line if there isn't one present in the command line. This can be disabled by passing the '-n' option to grub-emu. If the kernel is loaded from an ext2/3/4 partittion on disk and not iso, you will need to load the "ext2" module using the "insmod ext2" command. If you have a working grub.cfg on disk, avoid needing to issue commands at the grub prompt by specifying the relevant partition and root device when envoking grub-emu.
linux /isolinux/vmlinuz text earlyprintk=serial debug
initrd /isolinux/initrd.img
boot
For OpenBSD i386/amd64, the command to load the kernel is 'kopenbsd'. The "-h com0" option forces the use of the serial console - this should always be used with bhyve. The root device is specified with the "-r <sdX|wdX>" parameter.
kopenbsd -h com0 -r sd0a /bsd
boot
NetBSD/amd64 is booted with the 'knetbsd' command. Similar to OpenBSD, the "-h" and "-r" parameters should be used to specify a serial console and the root device.
knetbsd -h -r cd0a /netbsd
boot
FreeBSD/amd64 can be booted using the kfreebsd command. Note that grub will not automatically source any of the FreeBSD loader variable files, or interpret these as the FreeBSD loader does. The boot process will have to be manual unless a grub.cfg file has been created.
kfreebsd -h /boot/kernel/kernel
kfreebsd_loadenv /boot/device.hints
boot