Design Developing Software on Linux Tim Marriott Mel Nicholson ICCAD 2003

© 2003 Synopsys, Inc. (2) Introduction Why Linux? Porting to Linux Developing on Linux

© 2003 Synopsys, Inc. (3) Why Linux? The question should be “Why the PC?”  Inexpensive Performance What is wrong with Windows as the OS?  It is too different from Unix  Major EDA software runs on Unix  The initial port is tough and the continued support is difficult Linux is a robust OS that is very close to Unix  The initial port is easy and the continued support is also easy  It is in the right place at the right time

© 2003 Synopsys, Inc. (4) Why Linux? We port to Linux because customers want it  Fast Hardware  Inexpensive Hardware  It’s an easy port We develop on Linux because it increases our productivity  Fast Hardware  Inexpensive Hardware  Not a steep learning curve for our developers

© 2003 Synopsys, Inc. (5) Porting to Linux Porting Overview What Linux to choose? Problems with the Linux Support Story The Enterprise is Coming Porting Issues Encountered

© 2003 Synopsys, Inc. (6) Porting Overview Linux is really just another flavor of Unix  The port was not difficult  The issues encountered were no more difficult than between flavors of Unix Very few problems were encountered OS and hardware configuration took the most time to get right

© 2003 Synopsys, Inc. (7) What Linux to Choose? Versioned Linux was the gating factor to delivering a port  Can’t base a product on all variants of the OS that the open source community produces Various companies supply versioned variants of Linux  Red Hat, SuSE, Caldera, Mandrake  Synopsys chose Red Hat

© 2003 Synopsys, Inc. (8) Problems with the Linux Support Story Linux companies didn’t deliver a true enterprise support structure  Versions are not compatible  No long term support of versions  No compatibility guarantees between patches  Versions release very often ISV’s stay with old versions for long periods of time  Synopsys is still based on Red Hat 7.2 Linux companies have recognized the flaw  Enterprise versions are becoming available  Consumer versions are unfriendly to business

© 2003 Synopsys, Inc. (9) The Enterprise is Coming Red Hat now only supports an Enterprise version  Yearly subscription based support  Guaranteed binary and API compatibility between versions  months between major releases Cost will increase  Stability will offset the additional cost  Red Hat Enterprise Linux WS $179 - $299 on x86 $792 on Itanium and AMD64 Information on this slide from

© 2003 Synopsys, Inc. (10) Porting Issues Encountered Calling fclose() on a file that is not open crashes  Be sure to only call fclose() once per open file Binary files are not platform independent due to Little Endian byte order  Must decide where you want to handle the conversion when reading/writing binary files

© 2003 Synopsys, Inc. (11) Porting Issues Encountered Gcc doesn’t increment i++ until the end of the statement  result = foo(x[i++], x[i]);  Increment some other way i and i+1 is one option C compiler has problems with nested function calls and function calls in “if” statements  Use separate statements instead

© 2003 Synopsys, Inc. (12) Porting Issues Encountered “/bin” and “/usr/bin” are separate directories  Make sure command location is defined for Linux Default sorting order is not the same  Set environment variable LC_ALL to C

© 2003 Synopsys, Inc. (13) Porting Issues Encountered Can’t initialize global scope to be stdout or stdin  stdout/stdin are not constant expressions and are therefore not suitable for initialization If a NULL pointer is passed to fclose it will crash  Check the pointer if (fd) fclose(fd);

© 2003 Synopsys, Inc. (14) Porting Issues Encountered intptr_t is not defined in int_types.h  It is defined in stdint.h SIGEMT is not defined  Do not use SIGEMT

© 2003 Synopsys, Inc. (15) Porting Issues Encountered The default floating point precision varies  Uses native support of underlying hardware  Different results for register operation versus loaded  Makes golden-file based regression testing difficult  IEEE compliance options incur a performance penalty

© 2003 Synopsys, Inc. (16) Developing on Linux Linux Development Model Office Productivity Tools Developer Tools GUI Development

© 2003 Synopsys, Inc. (17) Linux Development Model Windows Desktop 2 CPU 4 GB Memory Linux Box Computer Room Exceed Vnc SCM Data Servers Big Local Disk

© 2003 Synopsys, Inc. (18) Office Productivity Tools Windows Desktop avoids the office productivity tool issues  OpenOffice and StarOffice available on Linux MS Office compatible  CodeWeavers CrossOver Office Allows MS Office to run directly on Linux  VMware dual operating system capable

© 2003 Synopsys, Inc. (19) Developer Tools Compilers  Gnu (gcc, g++)  Intel Compilers Debuggers  gdb  Graphical front end, ddd

© 2003 Synopsys, Inc. (20) Developer Tools Editors (IDE’s)  Emacs, Vim Highly configurable editors Can tightly integrate gdb and SCM systems  Kdevelop Full integrated MS Visual C++ style IDE Source Control Systems  Clearcase, Perforce, CVS, RCS

© 2003 Synopsys, Inc. (21) Developer Tools Memory Debug  Purify (Available Soon)  Valgrind Performance  Quantify (Available Soon)  Kcachegrind

© 2003 Synopsys, Inc. (22) Developer Tools Test Coverage  Purecov (Available Soon)  Gcov Scripting Language  Perl, Tcl/Tk, Python, JavaScript

© 2003 Synopsys, Inc. (23) GUI Development Native GUI toolkits available  Gnome GTK+ is a C based public domain toolkit  LessTiff is Motif compatible library  Tcl/Tk provides scripting type capabilities  Java, AWT or Swing  Qt is a C++ class library commercially available from Trolltech KDE is written in Qt Portable across Linux/Unix/Windows platforms Public Domain version available Synopsys standardized on Qt

© 2003 Synopsys, Inc. (24) Summary The PC has given us fast, inexpensive hardware Linux enables EDA on the PC Enterprise Linux makes this a viable solution  Stability, Compatibility, Predictability Linux is a winning platform for EDA!  For customers and developers