This is important since legacy bios mode is still the default for Intel
and AMD based instances on AWS. That is, even if your image is setup to
use UEFI on the OS level, the AMI will still use BIOS unless the boot
mode is explicitly set during registration.
Because this script enables `set -u` when no arguments are provided bash
exits with the error:
$1: unbound variable
instead of the helpful usage message.
For the case of blkfront drives, there appears to be no difference
between /dev/sda1 and /dev/xvda: the drive always appears as the
kernel device /dev/xvda.
For the case of nvme drives, the root device typically appears as
/dev/nvme0n1. Amazon provides the 'ec2-utils' package for their first
party linux ("Amazon Linux"), which configures udev to create symlinks
from the provided name to the nvme device name. This name is
communicated through nvme "Identify Controller" response, which can be
inspected with:
nvme id-ctrl --raw-binary /dev/nvme0n1 | cut -c3073-3104 | hexdump -C
On Amazon Linux, where the device is attached as "/dev/xvda", this
creates:
- /dev/xvda -> nvme0n1
- /dev/xvda1 -> nvme0n1p1
On NixOS where the device is attach as "/dev/sda1", this creates:
- /dev/sda1 -> nvme0n1
- /dev/sda11 -> nvme0n1p1
This is odd, but not inherently a problem.
NixOS unconditionally configures grub to install to `/dev/xvda`, which
fails on an instance using nvme storage. With the root device name set
to xvda, both blkfront and nvme drives are accessible as /dev/xvda,
either directly or by symlink.
As suggested in https://github.com/NixOS/nixpkgs/pull/39416#discussion_r183845745
the versioning attributes in `lib` should be consistent to
`nixos/version` which implicates the following changes:
* `lib.trivial.version` -> `lib.trivial.release`
* `lib.trivial.suffix` -> `lib.trivial.versionSuffix`
* `lib.nixpkgsVersion` -> `lib.version`
As `lib.nixpkgsVersion` is referenced several times in `NixOS/nixpkgs`,
`NixOS/nix` and probably several user's setups. As the rename will cause
a notable impact it's better to keep `lib.nixpkgsVersion` as alias with
a warning yielded by `builtins.trace`.
Unfortunately, somewhere between 16.09 and 17.03, paravirtualized
instances stopped working. They hang at the pv-grub prompt
("grubdom>"). I tried reverting to a 4.4 kernel, reverting kernel
compression from xz to bzip2 (even though pv-grub is supposed to
support xz), and reverting the only change to initrd generation
(5a8147479e). Nothing worked so I'm
giving up.
The EBS and S3 (instance-store) AMIs are now created from the same
image. HVM instance-store AMIs are also generated.
Disk image generation has been factored out into a function
(nixos/lib/make-disk-image.nix) that can be used to build other kinds
of images.
