```
nix-repl> pkgsCross.arm-embedded.stdenv.hostPlatform.emulatorAvailable pkgsCross.arm-embedded.buildPackages
false
nix-repl> pkgsCross.aarch64-multiplatform.stdenv.hostPlatform.emulatorAvailable pkgsCross.aarch64-multiplatform.buildPackages
true
```
will be useful for stuff like handling https://github.com/NixOS/nixpkgs/issues/187109
The comment in lib/systems/default.nix for uname.processor indicates that it
should match `uname -p`. I tried that command and found that it reports
`unknown` on all of these machines:
- `x86_64-linux`
- `aarch64-linux`
- `mips64el-linux`
- `powerpc64le-linux`
The command `uname -m` reports the expected value on all of the above.
I think the comment is wrong. So I fixed it.
In Nixpkgs, we assume that the "config" field is a canonicalized GNU
triple. I noticed that non-canonical values were being used here,
because the pkgsCross.mips64el-linux-gnu triples did not contain the
vendor field, but the pkgsCross.mips64el-linux-gnu.pkgsStatic did.
Here, I've run all the MIPS triples in lib.systems.examples through
config.sub to canonicalize them. I think this will avoid nasty
surprises in future.
Tested by building Nix and the bootstrap files for
pkgsCross.mips64el-linux-gnu.
This has been deprecated for a long time, and it's doubtful it had any
users to start with. And having an undisablable warning when
enumarating platforms is not good.
These servers apparently no longer exist, since September 2, 2021[1].
If somebody needs this for non-Scaleway machines, they should suggest
its reintroduction with a different name.
[1]: https://news.ycombinator.com/item?id=27192757
Very confusingly, the `isPowerPC` predicate in
`lib/systems/inspect.nix` does *not* match `powerpc64le`!
This is because `isPowerPC` is defined as
isPowerPC = { cpu = cpuTypes.powerpc; };
Where `cpuTypes.powerpc` is:
{ bits = 32; significantByte = bigEndian; family = "power"; };
This means that the `isPowerPC` predicate actually only matches the
subset of machines marketed under this name which happen to be 32-bit
and running in big-endian mode which is equivalent to:
with stdenv.hostPlatform; isPower && isBigEndian && is32bit
This seems like a sharp edge that people could easily cut themselves
on. In fact, that has already happened: in
`linux/kernel/common-config.nix` there is a test which will always
fail:
(stdenv.hostPlatform.isPowerPC && stdenv.hostPlatform.is64bit)
A more subtle case of the strict isPowerPC being used instead of the
moreg general isPower accidentally are the GHC expressions:
Update pkgs/development/compilers/ghc/8.10.7.nix
Update pkgs/development/compilers/ghc/8.8.4.nix
Update pkgs/development/compilers/ghc/9.2.2.nix
Update pkgs/development/compilers/ghc/9.0.2.nix
Update pkgs/development/compilers/ghc/head.nix
Since the remaining legitimate use sites of isPowerPC are so few, remove
the isPowerPC predicate completely. The alternative expression above is
noted in the release notes as an alternative.
Co-authored-by: sternenseemann <sternenseemann@systemli.org>
canExecute is like isCompatible, but also checks that the Kernels are
_equal_, i.e. that both platforms use the same syscall interface. This
is crucial in order to actually be able to execute binaries for the
other platform.
isCompatible is dropped, since it has changed semantically and there's
no use case left in nixpkgs.
Since we (exclusively) use isCompatible to gauge whether platform a can
execute binaries built for platform b, mode switching CPUs are not to be
considered compatible for our purposes: Switching the mode of a CPU
usually requires a reset. At the very least we can't execute a mix of
executables for the two modes which would usually be the case in nixpkgs
where we may want to execute buildInputs for the hostPlatform in
addition to nativeBuildInputs for the buildPlatform.
Since the list only gates the platforms the nixpkgs flake exposes
packages to build on, the `hydra` label made little sense. It was also
only used for this purpose, so the `tier*` attributes were largely
unnecessary.
To reflect the intention more accurately, we expose
`lib.systems.flakeExposed` and use it to gate flake.nix's system list.
This patch causes the autodetection code in lib/systems/platforms.nix
to return {} if it cannot detect the platform and one of the
platform.nix-detection-provided attributes (linux-kernel, gcc, and
rustc) are accessed, rather than silently assuming the "pc" platform
as was previously done.
It is definitely safe to assume that code using these attributes is
prepared to deal with `gcc` and `rustc` not being defined, because
many of the working entries in this file don't define it.
Regarding `linux-kernel` the situation is less certain, but some code
(`lib/systems/default.nix` for example) is already designed to deal
with that attribute being missing. At worst it would result in an
"attribute not found" error.
While adding mips64el bootstrap support to nixpkgs, the silent
assumption that mips64el routers are actually Intel PCs caused
significant frustration. This commit removes that assumption in order
to save people who port nixpkgs to new platforms in the future from
this frustration.
For other platforms like Intel and ARM, we can do
e.g. lib.platforms.aarch64 to get only the 64-bit ARM platorms, but
until now there were no equivalents for RISC-V.
There is only one ABI for 32-bit MIPS chips. Before mips64, it didn't
really have a name.
The 64-bit MIPS ABI comes in two flavors, "n64" and "n32". It is
commonplace to refer to the old 32-bit ABI as "o32" (MIPS and SGI
documents do this).
However, when configuring gcc, one must use --with-abi=32, not
--with-abi=o32.
Let's keep GCC happy with this commit.
This commit adds an `isPower64` predicate to the two existing
predicates for this architecture (`isPower` and `isPowerPC`).
Note that `isPowerPC` matches only 32-bit machines, whereas `isPower`
matches both 64-bit and 32-bit machines. Prior to this commit there
was no single `isXXX` predicate for `powerpc64le`.
MIPS has a large space of {architecture,abi,endianness}; this commit
adds all of them to lib/systems/platforms.nix so we can be done with
it.
Currently lib/systems/inspect.nix has a single "isMips" predicate,
which is a bit ambiguous now that we will have both mips32 and mips64
support, with the latter having two ABIs. Let's add four new
predicates (isMips32, isMips64, isMips64n32, and isMips64n64) and
treat the now-ambiguous isMips as deprecated in favor of the
more-specific predicates. These predicates are used mainly for
enabling/disabling target-specific workarounds, and it is extremely
rare that a platform-specific workaround is needed, and both mips32
and mips64 need exactly the same workaround.
The separate predicates (isMips64n32 and isMips64n64) for ABI
distinctions are, unfortunately, useful. Boost's user-scheduled
threading (used by nix) does does not currently supports mips64n32,
which is a very desirable ABI on routers since they rarely have
more than 2**32 bytes of DRAM.
While it is a fact of life that aarch64-darwin is built on Hydra, it has
never formally been elevated from the Tier 7 state it was originally
assigned in RFC 0046. Since platform Tier status is not only
descriptive, but also normative, a consensus to commit to supporting
aarch64-darwin would need to be reached.
