Add qemu_uefi_secure target for building Secure Boot images. These are
identical to qemu_uefi images with the exception that the test keys have
been installed into the flash image, enabling Secure Boot by default. In
addition, sign the grub binary with the test keys during build when
producing unofficial images.
This uses our new GRUB2 features to handle GPT priority partition
selection, terminal selection, OEM tweaks, etc. The old SYSLINUX and
PV-GRUB configs are now unused except for maintaining compatibility
with older installs. Of the old configs only the ones that
coreos-postinst copies are needed. The new setup supports using GRUB2
under Xen, giving us automatic fallback support on all of our platforms
for the very first time!
Since grub.cfg is copied into place instead of generated, build_image's
--boot_args option is no longer supported. It could be re-added later
with some sed goo but for now it is easy enough to just edit grub.cfg.
I am unsure exactly what situation is causing the loopback partition
device node to not exist when it is being mounted but this should help
work around the situation and log loudly about it so we can hopefully
figure out where to dig further.
This script replaces the standard grub-install tool to give us some more
control over what is going and ensure grub-install's auto-detection
magic doesn't make any incorrect choices. Also this script sets up a
loopback device and mounts the EFI partition in just the right way for
grub-bios-setup's auto-detection magic to work correctly.
I've chosen not to adapt disk_util to use partitioned loop devices to
make grub happy because ensuring loop devices get cleaned up properly
for the general case gets tricky and less robust.
