Frederic,
We may need to do a little more investigating/debugging to figure out why the .out file generated with CCS 5.4 does not work as expected, but let me start by offering a few points here:
The first thing to check would be to see if the project used the same compiler versions or different versions to build in the project in CCS 5.3 and 5.4. CCS 5.3.0.00090 came with C2000 compiler version 6.1.0 and CCS 5.4 comes with C2000 compiler version 6.1.3. Many times when users update their CCS version they still set their projects to use the older version of compiler tools with which the project was originally built to ensure bit-exact output . If you happen to know what version of compiler tools were used for the build in CCS 5.3, you can set the same version to be used with CCS 5.4. This wiki explains how. http://processors.wiki.ti.com/index.php/Projects_and_Build_Handbook_for_CCS#Changing_Compiler_versions
[quote user="Fred P"]Compiling the exact same project with CCS 5.2.1.0018 and 5.4.0.00091 gives two different .out files. However (and fortunately), .hex files are identical. CCS 5.4 basically outputs a bigger .out file but I can't tell more since it is all binary.[/quote]
The key is to check if both builds used the same version of compiler tools or different versions. You need to use the same version of compiler tools and same build options to ensure you get the same binary output.
If the project/executable was working fine with CCS 5.3 but started having problems with CCS 5.4, I would suggest first trying to build the project with the same version of compiler tools as was used with 5.3. If you are not sure which version that was, start with the default that came with 5.3, ie version 6.1.0. Set the project in CCS 5.4 to use compiler 6.1.0 as explained in the above wiki link and check that that works before moving on to upgrading to the newer compiler. Then if problems start to arise, you can debug further by determining if the problem is due to a compiler issue (different/incorrect code generated) or a runtime issue.