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PSP manipulation from DPMI programs (Developers)

posted by tkchia Homepage, 16.02.2023, 21:23
(edited by tkchia on 16.02.2023, 21:51)

Hello Laaca,

> Well, I don't know. It seems to me that "int 0x21, ax = 0x4b00" is maybe
> overkill. Modification of the parent's PSP (which will be inherited to
> child) seems to be easier for me. For now I solve it using a program
I am quite sure that Free Pascal's Exec() procedure, at the end of the day, invokes int 0x21, ax = 0x4b00 or something similar, and passes an explicit environment segment to the function. Because that is how the underlying MS-DOS system spawns child processes.

I think, rather than try to mess with the parent PSP data structures, a better way is to ask the Free Pascal maintainers whether there is a procedure that is like Exec() but allows you to add/replace environment variables for the child process — or if they intend to add such a procedure.

Thank you!

---
https://gitlab.com/tkchia · https://codeberg.org/tkchia · 😴 "MOV AX,0D500H+CMOS_REG_D+NMI"

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