[openblas] 01/01: Improve README.Debian for building a custom package

[Sébastien Villemot]

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sebastien pushed a commit to branch master
in repository openblas.

commit a178be5a247614491b8e578f814afd214d54217c
Author: Sébastien Villemot <sebastien at debian.org>
Date:   Wed Aug 2 14:31:12 2017 +0200

    Improve README.Debian for building a custom package
---
 debian/README.Debian | 49 +++++++++++++++++++++++++++++++++++--------------
 1 file changed, 35 insertions(+), 14 deletions(-)

diff --git a/debian/README.Debian b/debian/README.Debian
index 0e01bbc..7c1a382 100644
--- a/debian/README.Debian
+++ b/debian/README.Debian
@@ -1,11 +1,13 @@
 How to switch between the various BLAS/LAPACK implementations
 =============================================================
 
-BLAS:
-$ sudo update-alternatives --config libblas.so.3
+- BLAS:
 
-LAPACK:
-$ sudo update-alternatives --config liblapack.so.3
+ $ sudo update-alternatives --config libblas.so.3
+
+- LAPACK:
+
+ $ sudo update-alternatives --config liblapack.so.3
 
 More information is available at:
 
@@ -27,22 +29,41 @@ locally for optimal performance.
 If you want to create a custom OpenBLAS package, optimized for your specific
 machine, proceed as follows.
 
-Install the build dependencies:
+1) Install the build dependencies and the source of the package:
+
+ $ sudo apt-get build-dep openblas
+ $ apt-get source openblas
+
+2) Compile the package:
+
+ $ cd openblas-<UPSTREAM_VERSION>
+ $ DEB_BUILD_OPTIONS=custom dpkg-buildpackage -uc -b
+
+where <UPSTREAM_VERSION> is replaced with the appropriate value.
+
+3) When the build finishes, it should produce a .deb file, whose precise name
+you can figure out using:
+
+ $ ls ../libopenblas-base_*.deb
 
-$ sudo aptitude build-dep openblas
+Install it using:
 
-Get the sources of the package:
+ $ sudo dpkg -i ../libopenblas-base_<VERSION>_<ARCH>.deb
 
-$ apt-get source openblas
+replacing <VERSION> and <ARCH> with the appropriate values.
 
-Compile the package:
+4) If you don't want the Debian package manager to overwrite your optimized
+package with a generic one on system upgrades, you can mark the OpenBLAS
+package to be on hold, with the following command:
 
-$ cd openblas-<VERSION>
-$ DEB_BUILD_OPTIONS=custom dpkg-buildpackage -uc -b
+ $ sudo aptitude hold libopenblas-base
 
-It should produce a package that you can install with:
+Don't forget however to periodically check whether a more recent version of the
+package is available for the Debian suite that you are tracking, in which case
+you should go again through this procedure. The version check can be performed
+using:
 
-$ sudo dpkg -i ../libopenblas-base_<DEBVERSION>.deb
+ $ aptitude versions libopenblas-base
 
- -- Sébastien Villemot <sebastien at debian.org>, Thu, 27 Jul 2017 15:17:29 +0200
+ -- Sébastien Villemot <sebastien at debian.org>, Wed,  2 Aug 2017 14:30:28 +0200
  -- Sylvestre Ledru <sylvestre at debian.org>  Tue, 31 May 2011 13:56:22 +0200

-- 
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