me: well this is stupid, why did IBM sneak specifically Photoshop support under Win32s 1.30 and nothing else
ArcaOS: "we don't actually have a copy of the Win-OS2 source because it's encumbered by god knows how many companies"
me: i am once again asking myself how did i get here
thunks from hell
16-bit Windows calling a 32-bit driver pretending to be three VXDs in the VDM context which calls out to undocumented hooks in the OS/2 kernel to let Win32s allocations work
Win32s maintains a memory arena in the top half of the 32-bit address space. To run under OS/2, the IBM-supplied VW32S.SYS has to translate the VirtualAlloc/Free/etc calls and their flags and options into OS/2 VMAlloc/Free/etc calls.
It looks like Boca Raton added undocumented MVDM.DLL exports that give a VDM direct access to the OS2KRNL virtual memory management subsystem!
are you documenting all of this somewhere?
Katherine the Sixth
bitsavers.org