Something seems wrong / bizzare with the recursion in all-packages.nix
I've been trying to override linux_4_4 in my configuration.nix with the
following:
nixpkgs.config.packageOverrides = super:
{ linux_4_4 = super.linux_4_4.override { extraConfig = "CHROME_PLATFORMS
y";
kernelPatches = [ { name =
"f10_sysrq"; patch = ./f10_sysrq.patch; } ]; };
};
but this no longer works. I've spent a few hours studying the issue.
If I do the following chain of overrides upto the linuxPackages
attribute
nixpkgs.config.packageOverrides = super: rec
{ linux_4_4 = super.linux_4_4.override { extraConfig = "CHROME_PLATFORMS
y";
kernelPatches = [ { name =
"f10_sysrq"; patch = ./f10_sysrq.patch; } ]; };
linuxPackages_4_4 = super.recurseIntoAttrs (super.linuxPackagesFor
linux_4_4 linuxPackages_4_4);
linuxPackages = linuxPackages_4_4;
linux = linuxPackages.kernel;
};
then it does work.
I couldn't for the life of me understand why copying what is essentially
the exact definitions of linuxPackages_4_4 and linuxPackages into my
packageOverrides caused it to work. The whole point of the
packageOverride mechanism is to invoke late-binding so that I don't have
to override long chains.
I traced the issue to the following strange set of definitions:
all-packages.nix begins with something like this
{ ... }:
self: pkgs:
with pkgs;
{ ... }
It is a function of three arguments, (1) a set of parameters, (2) a
binding for self, (3) a binding for pkgs, and the with pkgs; bring all
the definitions from pkgs into scope.
This is called from top-level/default.nix with the following
expression:
allPackages = self: super:
let res = import ./all-packages.nix allPackagesArgs res self;
in res;
So allPackageArgs contains the parameters, self gets bound to res, and
pkgs get bound to self.
The upshot of this is that within all-packages.nix self (which is bound
to res) is the result of only evaluating all-packanges *with no
overrides* while pkgs (which is bound to self) ends up late-bound and is
the set of packges *with all overrides*
So when linux and linuxPackages get bound using self in all-packages:
# The current default kernel / kernel modules.
linuxPackages = self.linuxPackages_4_4;
linux = self.linuxPackages.kernel;
The use of self here (and throughout the linuxPackage definitions) means
that we are making reference to the *unoverridden package set*. This is
why my packageOverrides of linux_4_4 did nothing, because the references
to linux_4_4 inn all-packages.nix are prefixed with "self." which means
it always gets the unoverriden packages.
Is this really the desired behaviour? I think that all-packages.nix is
full of many questionable uses of the "self." prefix. I suspect that
people don't really understand that "self." means "give me the
unoverriden version of packages". I think renaming "self" in
all-packages.nix to "unoverridenPackages" would be a better name.
--
Russell O'Connor <http://r6.ca/>
``All talk about `theft,''' the general counsel of the American Graphophone
Company wrote, ``is the merest claptrap, for there exists no property in
ideas musical, literary or artistic, except as defined by statute.''
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