diff options
Diffstat (limited to 'doc/using/overlays.xml')
-rw-r--r-- | doc/using/overlays.xml | 31 |
1 files changed, 21 insertions, 10 deletions
diff --git a/doc/using/overlays.xml b/doc/using/overlays.xml index 5f808839dd0d0..ada9ab3893284 100644 --- a/doc/using/overlays.xml +++ b/doc/using/overlays.xml @@ -140,8 +140,8 @@ self: super: <section xml:id="sec-overlays-alternatives"> <title>Using overlays to configure alternatives</title> <para> - Certain software has different implementations of the same - interface. Other distributions have functionality to switch + Certain software packages have different implementations of the + same interface. Other distributions have functionality to switch between these. For example, Debian provides <link xlink:href="https://wiki.debian.org/DebianAlternatives">DebianAlternatives</link>. Nixpkgs has what we call <literal>alternatives</literal>, which @@ -160,8 +160,9 @@ self: super: </para> <para> The Nixpkgs attribute is <literal>openblas</literal> for - ILP64 and <literal>openblasCompat</literal> for LP64. This - is the default. + ILP64 (integer width = 64 bits) and + <literal>openblasCompat</literal> for LP64 (integer width = + 32 bits). <literal>openblasCompat</literal> is the default. </para> </listitem> <listitem> @@ -190,8 +191,15 @@ self: super: #83888</link>, we are able to override the ‘blas’ and ‘lapack’ packages to use different implementations, through the ‘blasProvider’ and ‘lapackProvider’ argument. This can be used - to select a different provider. For example, an overlay can be - created that looks like: + to select a different provider. BLAS providers will have + symlinks in <literal>$out/lib/libblas.so.3</literal> and + <literal>$out/lib/libcblas.so.3</literal> to their respective + BLAS libraries. Likewise, LAPACK providers will have symlinks + in <literal>$out/lib/liblapack.so.3</literal> and + <literal>$out/lib/liblapacke.so.3</literal> to their respective + LAPCK libraries. For example, Intel MKL is both a BLAS and + LAPACK provider. An overlay can be created to use Intel MKL + that looks like: </para> <programlisting> self: super: @@ -208,9 +216,12 @@ self: super: <para> This overlay uses Intel’s MKL library for both BLAS and LAPACK interfaces. Note that the same can be accomplished at runtime - using <literal>LD_PRELOAD</literal> of libblas.so.3 and - liblapack.so.3. + using <literal>LD_LIBRARY_PATH</literal> of libblas.so.3 and + liblapack.so.3. For instance: </para> + <programlisting> +$ LD_LIBRARY_PATH=$(nix-build -A mkl):$LD_LIBRARY_PATH nix-shell -p octave --run octave + </programlisting> <para> Intel MKL requires an <literal>openmp</literal> implementation when running with multiple processors. By default, @@ -221,8 +232,8 @@ self: super: set it with <literal>LD_PRELOAD</literal>. Note that <literal>mkl</literal> is only available on <literal>x86_64-linux</literal> and - <literal>x86_64-darwin</literal>. Moreover, Hydra is not build - and distributing pre-compiled binaries using it. + <literal>x86_64-darwin</literal>. Moreover, Hydra is not + building and distributing pre-compiled binaries using it. </para> <para> For BLAS/LAPACK switching to work correctly, all packages must |