Dealing with PM application problems under OS/2 2.x is similar to WARP. The principle difference being that the messaging and windowing function in PM is provided by the 16-bit DLL, PMWIN.DLL.

Most of the message structures are analogous to those of PMMERGE.DLL, their layouts are similar.

Under PMWIN.DLL most pointers are either offsets from a predefined segments or selectors. Thus where there are double-word pointers in PMMERGE.DLL structures, there are word length fields in PMWIN.DLL.

The following three symbol files are required for debugging PM applications problems under OS/2 2.x:

• PMWIN.SYM

• PMGRE.SYM

• PMSHAPI.SYM

A selection of useful symbols in the OS/2 2.x PM environment, with their equivalent OS/2 3.0 is listed below:

OS/2 3.0

OS/2 2.x

smqlist

smqsyslock

smqfocus

smqshell

smqshell2

pwndfocus

fBadAppDialog

qhpsBadApp

Another significant difference between the two environments is in the calling conventions:

• PMMERGE APIs use the 32-bit C calling convention

• PMWIN APIs use the 16-bit Pascal calling convention

In effect this means that parameters on stacks, and in some control blocks, are stored in reverse order.

There are four symbols that do not have equivalents in PMMERGE, these are:

winsel

The selector for the AAB regs segment for a process.

The selector for the SMS segment.

The table of WND heap pointers.

The PM FastSafe RAMSEM, which is equivalent to the User_Sem PM Semaphore of PMMERGE.

We now run through a brief sequence of examples that illustrate:

Finding an MQ and AAB registers

Finding an SMS from an MQ

Finding the WND from an HWND

Finding a BadApp process an MQ

Finding the System Queue