Package: liblapack-dev Version: 3.3.1-1 Severity: normal Tags: upstream Dear Maintainer,
When writing code that uses Lapack as well as threads (pthreads or OpenMP), certain routines, like the nonsymmetric eigensolver, produce incorrect results due to statically allocated arrays. The Lapack source uses large local arrays which are deemed by gfortran (by default) to be too large to allocate on the stack, leading to statically allocated variables which are corrupted when multiple threads write to them. Adding the "-frecursive" flag to the compilation flags would force gfortran to always allocate the arrays on the stack. The problem along with code to reproduce it has been listed in this forum post: http://icl.cs.utk.edu/lapack-forum/viewtopic.php?f=2&t=1930 The most ideal solution to the problem would be to modify the code to not use huge local arrays, but the API makes it impossible for several routines. Therefore, the use of compilation flags is a more immediate, but less elegant, fix. While I do not expect the addition of the flag to cause any side effects, there are a number of potential concerns. FIrst, more stack space will be used by the library. However, it will only be about a factor of 2 greater than the current situation, since the default variable size limit is 32KB, and the largest arrays in Lapack are around 64KB, and process stack size limits are in the range of several MB. Second, if this bug is fixed in Debian and its derivatives, porting scientific code that is affected by this bug to other systems may lead to confusion if the bug still exists with other platforms/compilers. -- System Information: Debian Release: wheezy/sid APT prefers precise-updates APT policy: (500, 'precise-updates'), (500, 'precise-security'), (500, 'precise') Architecture: amd64 (x86_64) Kernel: Linux 3.2.0-23-generic (SMP w/4 CPU cores) Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Versions of packages liblapack-dev depends on: ii libatlas-base-dev [libblas-3gf.so] 3.8.4-3build1 ii libblas-dev [libblas-3gf.so] 1.2.20110419-2ubuntu1 ii liblapack3gf 3.3.1-1 ii libopenblas-dev [libblas-3gf.so] 0.1alpha2.2-3 liblapack-dev recommends no packages. liblapack-dev suggests no packages. -- no debconf information -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org