When building an image, rather than operating on a real partition,
there's no need to have sfdisk tell the kernel to reread the partition
table. This also avoids a call to sync(2), which could be very
expensive depending on what other IO is going on on the system at the time.
The comment says this is required by other modules but to be honest, I
cannot see where. Bootloaders will be included automatically by nixos
generation if their `installBootLoader` attribute references it.
This helps us to make kexec images even smaller espeically when
combined with the perlless profile.
these changes were generated with nixq 0.0.2, by running
nixq ">> lib.mdDoc[remove] Argument[keep]" --batchmode nixos/**.nix
nixq ">> mdDoc[remove] Argument[keep]" --batchmode nixos/**.nix
nixq ">> Inherit >> mdDoc[remove]" --batchmode nixos/**.nix
two mentions of the mdDoc function remain in nixos/, both of which
are inside of comments.
Since lib.mdDoc is already defined as just id, this commit is a no-op as
far as Nix (and the built manual) is concerned.
PR #256638 inadvertently introduced a bug in `nixos-generate-config` whereby it
would never put `bcache` into the `availableKernelModules` for the initrd.
This is because the `qr` operator in Perl returns a regex object, rather than
matching it; the regex object evaluates to true, making the filter expression
effectively `grep(!true, @bcacheDevices)`, which will always return an empty
list.
Right now the worst case chain of events for building an ISO on Hydra is
- copy everything to squashfs builder
- run squashfs builder
- download squashfs from builder
- compress squashfs
- upload squashfs to S3
- copy squashfs to ISO builder
- run ISO builder
- download ISO from builder
- compress ISO
- upload ISO to S3
This inlines the squashfs build into the ISO build, which makes it
- copy everything to ISO builder
- run ISO builder
- download ISO from builder
- compress ISO
- upload ISO to S3
Which should reduce queue runner load by $alot per ISO, which we have four of on small channels
(one release, one test per arch) and a lot more than four of on large channels (with various desktops)
this lets us *dis*able filesystem explicitly, as is required by e.g. the
zfs-less installer images. currently that specifically is only easily
possible by adding an overlay that stubs out `zfs`, with the obvious
side-effect of also removing tooling that could run without the kernel
module loaded.
When building kexec-based installer every mb saved will reduce the RAM usage and allow to install NixOS on smaller machines.
It also means that less data has to be downloaded from the network.
When using flakes or niv we no longer rely on nix channels beeing present
and when using something like nixos-anywhere, we no longer need to evaluate anything in the installer at all.
This script would always "detect" the "powersave" governor as it is available on
practically all CPUs while the "ondemand" governor is only available on some old
CPUs.
IME the "powersave" governor barely provides any power savings but introduces
massive performance deficits, including noticable stuttering. This is not the
default experience we should offer users, even for those who use laptops.
Use the kernel default (currently "performance", CPU makers may change it in
future) instead.
