From: muta...@gmail.com   
      
   On Thursday, July 1, 2021 at 4:45:47 PM UTC+10, James Harris wrote:   
      
   > app --> yourcode --> something privileged   
   >   
   > then (unless the privileged code will reflect invocations to yourcode)   
   > those apps could not use software interrupts to get to yourcode but you   
   > could have libraries which the apps can call. Ideally, the app would say   
   > something like   
   >   
   > pdos_write(chan, "Hello", 5)   
   >   
   > where pdos_write would be in a library you've supplied which will, if   
   > necessary, go on to invoke the relevant routine in yourcode.   
   >   
   > Ideally, IMO, pdos_write would be dynamically linked so it would not   
   > have to be part of the app binary.   
      
   Yes, this is exactly what I want - so long as pdos_write is   
   in a dynamic library (or probably even better, a UEFI-like   
   library provided at program entry), all is fine.   
      
   It's only when pdos_write is statically linked that the   
   executable suddenly gets an INT hardwired into it,   
   and suddenly the caller needs to have ensured that   
   an appropriate interrupt vector exists. Which may   
   be impossible, because the caller may be an   
   unprivileged version of PDOS.   
      
   > > Any application that does any interrupt won't work.   
   > >   
   > > Win32 executables should work, although I haven't   
   > > definitively proven that DLLs can be handled.   
      
   > The bottom line is that, AISI, apps should only have to include standard   
   > calls (no ints, no sysenters etc), and it is the OS or library which   
   > should supply the code which they call. That's not unusual. I think it's   
   > how OSes normally make their service routines available.   
      
   Sure, that is not in dispute. It's whether the library is   
   statically linked and contains an interrupt, or in the case   
   of AmigaOS, an expectation of address 4 being set to   
   something special. Or directly manipulating hardware.   
   Or setting or inspecting segment registers.   
      
   BFN. Paul.   
      
   --- SoupGate-Win32 v1.05   
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