diff options
| author | Robin Gloster <mail@glob.in> | 2021-05-24 09:55:24 -0500 |
|---|---|---|
| committer | Robin Gloster <mail@glob.in> | 2021-05-24 09:55:24 -0500 |
| commit | 4bc5fbef9d159e143fb7e2c3231932e6e76f667c (patch) | |
| tree | e2198f5c552e0667d838b8ec764ddb3a4d8f6dec /lib/systems/parse.nix | |
| parent | jq: fix build with structured-attrs on darwin (diff) | |
| parent | Merge pull request #123802 from superherointj/package-virtmanager-bugfix (diff) | |
| download | nixpkgs-origin/structured-attrs.tar.gz | |
Merge remote-tracking branch 'upstream/master' into structured-attrsorigin/structured-attrs
Diffstat (limited to 'lib/systems/parse.nix')
| -rw-r--r-- | lib/systems/parse.nix | 23 |
1 files changed, 14 insertions, 9 deletions
diff --git a/lib/systems/parse.nix b/lib/systems/parse.nix index a06ac0d11f74..accaeb652d07 100644 --- a/lib/systems/parse.nix +++ b/lib/systems/parse.nix @@ -121,15 +121,20 @@ rec { js = { bits = 32; significantByte = littleEndian; family = "js"; }; }; - # Determine where two CPUs are compatible with each other. That is, - # can we run code built for system b on system a? For that to - # happen, then the set of all possible possible programs that system - # b accepts must be a subset of the set of all programs that system - # a accepts. This compatibility relation forms a category where each - # CPU is an object and each arrow from a to b represents - # compatibility. CPUs with multiple modes of Endianness are - # isomorphic while all CPUs are endomorphic because any program - # built for a CPU can run on that CPU. + # Determine when two CPUs are compatible with each other. That is, + # can code built for system B run on system A? For that to happen, + # the programs that system B accepts must be a subset of the + # programs that system A accepts. + # + # We have the following properties of the compatibility relation, + # which must be preserved when adding compatibility information for + # additional CPUs. + # - (reflexivity) + # Every CPU is compatible with itself. + # - (transitivity) + # If A is compatible with B and B is compatible with C then A is compatible with C. + # - (compatible under multiple endianness) + # CPUs with multiple modes of endianness are pairwise compatible. isCompatible = a: b: with cpuTypes; lib.any lib.id [ # x86 (b == i386 && isCompatible a i486) |