My primary use case for this flag is to fix booting with UEFI firmware
which can have problems when mixed with KVM, adding kexec into the mix
doesn't help matters either. The current version of OVMF can boot from
virtio drives just fine so that is now enabled and KVM is disabled.
So the -s option can also mean sloooooooow but boots!
The new grub install script must be called after the image is unmounted
and the old bootloaders script doesn't need to touch grub at all. For
now we will continue to use the existing syslinux configs but
interpreted by grub. Beyond the grub menu flashing by during boot
everything should still be functionally equivalent.
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.
The passing ROOT= as an environment variable to board wrapper scripts
doesn't work, the script unconditionally overrides it. This means so far
our packages.txt files have listed the contents of /build/amd64-usr
instead of the image. Fix this by calling equery directly instead.
previously check_etag.sh would not create a blank file if it did
not exist. The result was that the first time check_etag.sh was
run it would always exit non-zero.
Currently building images on older kernels will fail because mkfs.btrfs
enables an incompatible feature 'extref' by default. We never really
made this requirement explicit and the SDK in general has continued to
maintain compatibility with older kernels. Make the requirement explicit
so users will get errors quicker and there is a clear line for what
kernel features can be used in the SDK.
Not currently used, this configuration which sets up grub to re-use the
syslinux configuration only works with recent git versions, not any
releases. Compatibility is also limited because the serial configuration
in syslinux must be duplicated in the grub config.
We don't need to do anything like manually install the MBR boot code
for grub but we do need to continue to expose the ESP partition as a
hybrid partition to support pvgrub.
Calling cgpt create when resizing zeros the MBR boot code. This worked
with the syslinux setup because the boot code was re-written. When not
using syslinux it is easier to just preserve the existing MBR instead.
Unlike SYSLINUX, GRUB2 does not recommend embedding itself in a FAT
filesystem. Instead GRUB2 prefers embedding in the space between the MBR
and first partition or using a dedicated partition that is safe from
tampering by fs utilities. In our case the space after the MBR is where
the GPT lives so we need to use the extra partition scheme instead.
The 64MB "BOOT-B" partition has never been used so we can replace it
with a 2MB partition which is more than enough for GRUB.
We have long since stopped installing anything to the /boot directory of
the root filesystem. Mount the ESP partition to /boot for consistancy
with the discoverable partition spec.
Normally GCC is installed in a way that allows installing multiple
versions and switching between them. Our production images do not need
this and additionally the only things from the GCC package that are
needed are the shared libraries. To ensure these libraries are *always*
locatable regardless of the presence of /etc/ld.so.conf and
/etc/ld.so.cache we can install those libraries to plain old /usr/lib.
The GCC packages don't have a built in way to do this but we can get
away with extracting the libraries directly from the binary package.
This is actually similar to what ChromeOS did with a few exceptions:
- We use a native GCC build instead of the cross toolchain
- The archive is properly extracted from the package instead of feeding
the package directly to tar and ignoring the resulting warnings.
As an added benefit switching from a blacklist to a whitelist ensures
that extra cruft does not slip through the cracks, saving 5-10MB.
Create profile as a real directory instead of a symlink to the board
root's configuration. Normally the board root does not modify this but
it is useful for build_image to use it to modify package.provided.
Normally Gentoo expects moving between major GCC releases to be a manual
step. In our case we want this to always be automatic, otherwise the GCC
version won't be switched at all.
Apparently expanding an empty string before a variable assignment forces
that assignment to be interpreted as a command instead. Instead of an
empty string use env as our sudo alternative when running as root.
Newer git ebuilds have decided that the "git-prompt" script isn't really
bash completion so stopped installing it via that mechanism. Instead it
installed it started installing it in /usr/share/docs which gets
compressed by default and the path is based on ebuild version. The path
changed again in 1.9.3 to /usr/share/git and didn't compress it so that
makes it actually possibly usable but 1.9.3 or later isn't stable yet.
We can re-enable it the next time git gets updated but not worth fussing
over the current brokenness right now.
If additional EBS volumes are mapped to a PV instance using a "sd*" name
they will always be ordered by the hypervisor before "xvd*" devices,
again ignoring the root device definition. This applies to all PV
instance types so we cannot get away with just poo-pooing m1.small.
We will need to call attention to this since it requires users who set
the volume size via APIs to use the name "/dev/sda" again.
