Currently, you need to override `stdenv.hostPlatform` to request a
compressed kernel on AArch64, and the kernel configuration is split
between the central structured configuration and string snippets in
platform definitions. This has consequently made the latter bitrot
terribly. Since the platform‐specific logic is now very limited after
cleaning up the detritus, we can move it into the kernel derivation
and expose the relevant configuration there for anyone who wants to
customize it further or needs to read it out.
Co-authored-by: zowoq <59103226+zowoq@users.noreply.github.com>
The `sheevaplug` kernel configuration was added a very long time
ago and has not been adjusted for years. `pogoplug4` was identical
to `sheevaplug` except for an even more stripped‐down kernel
configuration, no device tree support, and a different load address
for the uImage.
These days, the stock kernel configuration builds and there has been
an upstream device tree for the Pogoplug Series 4 for years; unify
`sheevaplug` and `pogoplug4` into an `armv5tel-multiplatform` that
uses the standard configuration.
ARMv5 was also the only platform that defaulted to uImage, the [legacy
U‐Boot image format] that is deprecated upstream. Our bootloader
machinery in NixOS does not handle these images in any special way
and even the original ARMv6 Raspberry Pi platform defaults to the
standard zImage. We switch `armv5tel-multiplatform` to zImage to match.
[legacy U‐Boot image format]: https://docs.u-boot.org/en/latest/usage/cmd/bootm.html#legacy-boot
It is of course natural to worry about backwards compatibility
here: this switches to a different kernel image format and drops
support for root on NFS along with random oddities like KGDB and
LatencyTOP. Renaming the platform is intended to help mitigate
this risk.
The reality, however, is that it is currently very
difficult to build a configuration for ARMv5. I found
<https://github.com/thefloweringash/sheevaplug-nix> online as
an example configuration from many years ago; it already set
`autoModules`, and builds U‐Boot using `CONFIG_DISTRO_DEFAULTS`,
which should work out of the box without requiring the legacy U‐Boot
image format.
Even then, however, I confirmed with the author that it hasn’t
been used in years, and I could barely get it to build with
a modern Nixpkgs: OpenSSH is broken, Nix is broken, multiple
default `environment.systemPackages` in the SD image profile
are broken, `boot.initrd.includeDefaultModules` is broken, and
`hardware.enableAllHardware` is broken.
I conclude that if anyone is actively building systems on ARMv5, they
have a forked Nixpkgs or a very custom setup. Given our general move
to standard boot chains and no platform‐specific hacks, and the
decaying state of our unofficial support for 32‐bit ARM, I think
it is not worth maintaining support for the legacy image format for
this one ancient platform.
If anyone is running a heavily stripped‐down NixOS configuration on
mission‐critical SheevaPlugs using a custom Nix‐free deployment
setup relying on the legacy U‐Boot image format and somehow none
of these kernel changes manage to loudly break their build, hopefully
they’ll at least notice the release notes entry! Otherwise there’s
always JTAG…
These were not used by the selection logic or
`lib/systems/examples.nix`, so any consumer would have to be including
them explicitly. Since we’re moving away from setting Linux kernel
configuration in the platform structure, breaking these explictily
won’t reduce the convenience and will help signal to any such expert
users that they need to move their kernel configuration elsewhere.
None of these successfully build a kernel, and as we’re moving
away from putting kernel configuration in the platform structure and
don’t package the vendor kernels that all but `fuloong2f_n32` expect,
there’s no point to keeping these kernel configurations in Nixpkgs.
- Pass --with-multilib-list=m4,m4-nofpu for SH4 so the kernel can use
-m4-nofpu. Move libraries out of !m4/ multilib subdirectory in
postInstall before moveToOutput.
- Generate sysroot-suffix.h for SH4 in the standalone libgcc builder.
- Add linux-kernel.target = "vmlinux" and installTarget for SH4.
All changes scoped to isSh4 to avoid rebuilds on other platforms.
Add sh4 CPU type (32-bit, little-endian, family "sh"), isSh4 predicate,
"sh4-linux" system double, cross-compilation example (sh4-unknown-linux-gnu),
linuxArch mapping to "sh", and test entry.
Add arc CPU type (32-bit, little-endian, family "arc"), isArc
predicate, arc-linux double, arc cross example with
arc-unknown-linux-gnu triple, and release-cross job.
ARC has glibc support and uses the "arc" Linux kernel arch, which
matches the CPU name so no explicit linuxArch mapping is needed.
Use lib.filter and lib.attrNames instead of builtins.* directly,
consistent with the rest of the file's style.
Follow-up to #506588, incorporating review feedback from #507232.
`qemuArch` returned "aarch64" for both LE and BE, causing binfmt to
register `qemu-aarch64` for `aarch64_be` binaries. QEMU ships separate
`qemu-aarch64` and `qemu-aarch64_be` binaries, so the wrong interpreter
was used, failing with "Invalid ELF image for this architecture".
Since QEMU distinguishes endianness in the binary name, this adds the
"_be" suffix via `isBigEndian`, which is similar to the approach MIPS
uses a few lines below.
- concrete types start with uppercase: Int, String, Bool, Derivation,
etc.
- type variables start with lowercase: a, b, etc.
- list:
- use `[x]` for homogeneous lists instead of `List x` or `[ x ]`
- use `List` for heterogeneous lists (not that common in `lib`)
- attr:
- use `AttrSet` for a generic attribute set type
- use `{ key1 :: Type1; key2 :: Type2; ... }` for adding signatures
for known attribute names and types
- use `{ key1 = value1; key2 = value2; ... }` for adding attributes
with known literals
- end with an ellipsis (`...`) if the set can contain unknown
attributes
- use `{ [String] :: x }` if all the attributes has the same type `x`
- prefer `Any` over `a` if the latter is not reused
Make rustcTargetSpec the primary entrypoint for setting a custom target,
and wire up all the other stuff so they are hopefully as working and as
broken as before.
In particular, to specify a custom target, the user now just specifies
rust.rustcTargetSpec. rust.platform and rust.cargoShortTarget are
populated from rust.rustcTargetSpec now. In addition, rust.rustcTarget
defaults to rust.cargoShortTarget. (rust.rustcTarget and
rust.cargoShortTarget really should always be the same, but I think we
can deal with that later).
This allows the user to more easily control the basename of
rust.rustcTargetSpec by passing e.g.
"${./rust}/mips64el_mips3-unknown-linux-gnuabi64.json", which allows
cc-rs and in turn std to work.
Emily