diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/using/overlays.chapter.md | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/doc/using/overlays.chapter.md b/doc/using/overlays.chapter.md index df152bc14e7..a51aa9ee8fc 100644 --- a/doc/using/overlays.chapter.md +++ b/doc/using/overlays.chapter.md @@ -77,7 +77,7 @@ In Nixpkgs, we have multiple implementations of the BLAS/LAPACK numerical linear The Nixpkgs attribute is `openblas` for ILP64 (integer width = 64 bits) and `openblasCompat` for LP64 (integer width = 32 bits). `openblasCompat` is the default. -- [LAPACK reference](http://www.netlib.org/lapack/) (also provides BLAS) +- [LAPACK reference](http://www.netlib.org/lapack/) (also provides BLAS and CBLAS) The Nixpkgs attribute is `lapack-reference`. @@ -117,7 +117,23 @@ $ LD_LIBRARY_PATH=$(nix-build -A mkl)/lib${LD_LIBRARY_PATH:+:}$LD_LIBRARY_PATH n Intel MKL requires an `openmp` implementation when running with multiple processors. By default, `mkl` will use Intel's `iomp` implementation if no other is specified, but this is a runtime-only dependency and binary compatible with the LLVM implementation. To use that one instead, Intel recommends users set it with `LD_PRELOAD`. Note that `mkl` is only available on `x86_64-linux` and `x86_64-darwin`. Moreover, Hydra is not building and distributing pre-compiled binaries using it. -For BLAS/LAPACK switching to work correctly, all packages must depend on `blas` or `lapack`. This ensures that only one BLAS/LAPACK library is used at one time. There are two versions of BLAS/LAPACK currently in the wild, `LP64` (integer size = 32 bits) and `ILP64` (integer size = 64 bits). Some software needs special flags or patches to work with `ILP64`. You can check if `ILP64` is used in Nixpkgs with `blas.isILP64` and `lapack.isILP64`. Some software does NOT work with `ILP64`, and derivations need to specify an assertion to prevent this. You can prevent `ILP64` from being used with the following: +To override `blas` and `lapack` with its reference implementations (i.e. for development purposes), one can use the following overlay: + +```nix +self: super: + +{ + blas = super.blas.override { + blasProvider = self.lapack-reference; + }; + + lapack = super.lapack.override { + lapackProvider = self.lapack-reference; + }; +} +``` + +For BLAS/LAPACK switching to work correctly, all packages must depend on `blas` or `lapack`. This ensures that only one BLAS/LAPACK library is used at one time. There are two versions of BLAS/LAPACK currently in the wild, `LP64` (integer size = 32 bits) and `ILP64` (integer size = 64 bits). The attributes `blas` and `lapack` are `LP64` by default. Their `ILP64` version are provided through the attributes `blas-ilp64` and `lapack-ilp64`. Some software needs special flags or patches to work with `ILP64`. You can check if `ILP64` is used in Nixpkgs with `blas.isILP64` and `lapack.isILP64`. Some software does NOT work with `ILP64`, and derivations need to specify an assertion to prevent this. You can prevent `ILP64` from being used with the following: ```nix { stdenv, blas, lapack, ... }: |