11.3.4.2 Object Compatibility Model [DD]

Since functions in secure segments set PSVPAG to their respective psv constant sections, a convention must be established for managing multiple values of the PSVPAG register. In previous versions of the compiler, a single value of PSVPAG was set during program startup if the default constants-in-code memory model was selected. The compiler relied upon that preset value for accessing const variables and string literals, as well as any variables specifically nominated with space(auto_psv).

MPLAB XC-DSC provides support for multiple values of PSVPAG. Variables declared with space(auto_psv) may be combined with secure segment constant variables and/or managed psv variables in the same source file. Precompiled objects that assume a single, pre-set value of PSVPAG are link-compatible with objects that define secure segment psv constants or managed psv variables.

Even though PSVPAG is considered to be a compiler-managed resource, there is no change to the function calling conventions.