runqemu: support UEFI with OVMF firmware

In the simplest case, "runqemu qemux86 <some-image> qcow2 ovmf" for an
EFI-enabled image in the qcow2 format will locate the ovmf.qcow2
firmware file deployed by the ovmf recipe in the image deploy
directory, override the graphics hardware with "-vga std" because that
is all that OVMF supports, and boot with UEFI enabled.

ovmf is not built by default. Either do it explicitly ("bitbake ovmf")
or make it a part of the normal build
("MACHINE_ESSENTIAL_EXTRA_RDEPENDS_append = ' ovmf'").

The firmware file is activated as a flash drive instead of using the
qemu BIOS parameters, because that is the recommended method
(https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=764918#47) as it
allows storing UEFI variables in the file.

Instead of just "ovmf", a full path to an existing file can also be
used, just as with the rootfs. That may be useful when making a
permanent copy of the virtual machine data files.

It is possible to specify "ovmf*" parameters more than once, then
each parameter creates a separate flash drive. This way it is possible
to use separate flash drives for firmware code and variables:
$ runqemu qemux86 <some-image> qcow2 ovmf.code ovmf.vars"

Note that rebuilding ovmf will overwrite the ovmf.vars.qcow2 file in
the image deploy directory. So when the goal is to update the firmware
while keeping variables, make a copy of the variable file and use
that:
$ mkdir my-machine
$ cp tmp/deploy/images/qemux86/ovmf.vars.qcow2 my-machine/
$ runqemu qemux86 <some-image> qcow2 ovmf.code my-machine/ovmf.vars.qcow2

When Secure Boot was enabled in ovmf, one can pick that instead of
the non-Secure-Boot enabled ovmf.code:
$ runqemu qemux86 <some-image> qcow2 ovmf.secboot.code my-machine/ovmf.vars.qcow2

Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>

0 files changed, 0 insertions, 0 deletions