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Ways to modify OpenIFS
There are several ways in which code changes to OpenIFS could be managed:
- Edit code in the
oifs/src
directory directly (not recommended).
Code changes can be hard to track and integrating new versions of the model becomes difficult. - Place OpenIFS source in a version control system (e.g. subversion or git) and edit the code in
oifs/src
. - Leave code in
oifs/src
'as-is' and place modified or new code in new directories (recommended)
This has the advantage that multiple code developments can be maintained in separate directories; code changes are easy to see and integrating new versions of the model source straightforward. A version control system can also be used.
We recommend maintaining all code changes outside the main oifs/src
directory. It makes use of a facility provided by the FCM build software called 'inherited builds'. This is explained below in a series of examples.
The example configuration files for FCM can be downloaded from....
Inherited builds with FCM
In essence an inherited build is where the build (i.e. compilation) settings for OpenIFS are not altered but are used or inherited by a new FCM configuration file placed in a separate directory. The new FCM configuration file only needs to specify what's different about the build, either the sources or compilation settings. The rest of the information is obtained by telling FCM to look at the OpenIFS configuration. A user may have a number of these separate configuration files each in separate directories for developing or testing independent code changes.
Example1: Modifying compilation options
HowTo customise compiling OpenIFS explains how environment variables and editing the configuration files can alter the compiler settings for OpenIFS. In this simple example, an inherited build is used to achieve the same effect by creating a separate configuration file.
The advantage of this approach is that the source code and configuration files of OpenIFS are left unaltered.
Create directories for your own configuration files and source code. For example, create 'oifs/mymake
' in which to put your own configuration files and 'oifs/mysrc
' to put your own source code:
% cd oifs % mkdir mysrc mymake % ls COPYING ChangeLog INSTALL LICENSE NOTICE README html make mymake mysrc src t21test % cd mymake
The OpenIFS source code is in 'src
' with the compilation configurations files used by the FCM build software in 'make/fcmcfg
'.
In the 'oifs/mymake
' directory, create a file called 'change-fcflags.cfg
' with the following content:
use = ../make include = ../make/fcmcfg/oifs.cfg # Add array bound checking to some routines for debugging build.prop{fc.flags}[ifs/phys_radi/uvclr.F90] = $OIFS_FFLAGS -fcheck=bounds
Now run the fcm command to build the model with this change:
% fcm make -v -f change-fcflags.cfg [init] make # 2013-02-25 17:20:06Z [init] make config-parse # 2013-02-25 17:20:06Z [info] config-file=/openifs/inherit_tests/oifs/mymake/change-fcflags.cfg [info] config-file= - /openifs/inherit_tests/oifs/make/fcmcfg/oifs.cfg [info] config-file= - - /openifs/inherit_tests/oifs/make/fcmcfg/x86_64-gnu-opt.cfg [done] make config-parse # 0.3s [init] make dest-init # 2013-02-25 17:20:06Z [info] dest=nagc@elvira:/openifs/inherit_tests/oifs/mymake [info] mode=new [info] use=/openifs/inherit_tests/oifs/make [done] make dest-init # 0.0s [init] make build # 2013-02-25 17:20:06Z [info] sources: total=2192, analysed=0, elapsed-time=0.6s, total-time=0.0s [info] target-tree-analysis: elapsed-time=13.3s [info] compile 0.2 M uvclr.o <- ifs/phys_radi/uvclr.F90 [info] link 1.7 M master.exe <- programs/master.F90 [info] compile targets: modified=1, unchanged=2070, total-time=0.2s [info] compile+ targets: modified=0, unchanged=626, total-time=0.0s [info] ext-iface targets: modified=0, unchanged=1247, total-time=0.0s [info] install targets: modified=0, unchanged=120, total-time=0.0s [info] link targets: modified=1, unchanged=0, total-time=1.7s [info] TOTAL targets: modified=2, unchanged=4063, elapsed-time=25.3s [done] make build # 26.3s [done] make # 26.6s
Note!
Before running this example, make sure you have built the model by using the 'fcm make
' command in the 'oifs/make
' directory.