F.2 Before starting

When the makeles should be used, the above directory tree must be used.

The compiler and rtl source are zipped in such a way that when both are unzipped in the same directory (/pp/src in the above) the above directory tree results.

There are 2 ways to start compiling the compiler and RTL. Both ways must be used, depending on the situation. Usually, the RTL must be compiled rst, before compiling the compiler, after which the compiler is compiled using the current compiler. In some special cases the compiler must be compiled rst, with a previously compiled RTL.

How to decide which should be compiled rst? In general, the answer is that the RTL should be compiled rst. There are 2 exceptions to this rule:

1. The rst case is when some of the internal routines in the RTL have changed, or if new internal routines appeared. Since the OLD compiler doesn't know about these changed internal routines, it will emit function calls that are based on the old compiled RTL, and hence are not correct. Either the result will not link, or the binary will give errors.
2. The second case is when something is added to the RTL that the compiler needs to know about (a new default assembler mechanism, for example).

How to know if one of these things has occurred? There is no way to know, except by mailing the Free Pascal team. When the compiler cannot be recompiled when rst compiling the RTL, then try the other way.