Author Topic: dead "VDM" entry in process list  (Read 927 times)

Martin Vieregg

  • Jr. Member
  • **
  • Thank You
  • -Given: 0
  • -Receive: 3
  • Posts: 62
    • View Profile
dead "VDM" entry in process list
« on: May 11, 2018, 03:35:05 pm »
in the TOP process list, I always have got a dead "VDM" entry (virtual DOS machine), a DOS or a Win16 session. I have not started it. I have got a new ArcaOS 5.0.2 instalation. Any ideas? Is there an ArcaOS user with or with not this entry?

My interest is the question that I cannot start windowed DOS or seamless Win16. (That's a documented problem a lot of users have.) Perhaps there's a connection between these two effects.

I cannot kill the "VDM" entry. I cannot see this in the GO or MOLE process list, and of course not in the OS/2 window list.

OS4User

  • Full Member
  • ***
  • Thank You
  • -Given: 11
  • -Receive: 6
  • Posts: 156
    • View Profile
Re: dead "VDM" entry in process list
« Reply #1 on: May 11, 2018, 06:01:26 pm »
in the TOP process list, I always have got a dead "VDM" entry

it is not dead  -  it is alive :)

it is a miniVDM for getting int10 service from protected mode code

Pete

  • Hero Member
  • *****
  • Thank You
  • -Given: 1
  • -Receive: 28
  • Posts: 669
    • View Profile
Re: dead "VDM" entry in process list
« Reply #2 on: May 11, 2018, 08:12:32 pm »
Hi

You get the "dead "VDM" entry" even when there is no DOS/Win16 support installed - even after "tidying up" by deleting the MDOS directory and deleting all DOS related config.sys lines.


Regards

Pete

Martin Vieregg

  • Jr. Member
  • **
  • Thank You
  • -Given: 0
  • -Receive: 3
  • Posts: 62
    • View Profile
Re: dead "VDM" entry in process list
« Reply #3 on: May 12, 2018, 08:51:53 am »
But I need Win16. On my older computer (eCS 1.2), I have not this entry.

I have no problems with this entry, if it has got nothing to do with the seamless/DOS window problem.

Lars

  • Sr. Member
  • ****
  • Thank You
  • -Given: 0
  • -Receive: 28
  • Posts: 253
    • View Profile
Re: dead "VDM" entry in process list
« Reply #4 on: May 15, 2018, 01:55:20 pm »
But I need Win16. On my older computer (eCS 1.2), I have not this entry.

I have no problems with this entry, if it has got nothing to do with the seamless/DOS window problem.

This "VDM" is started by Panorama because Panorama has to access the real mode BIOS in order to do its video mode selection/management etc.
For that Panorama directly issues the documented real mode DOS video interrupt calls. These calls can only be executed by the VDM.

By the way: DANIS506.ADD (and of course IBMS506.ADD) can start a "VDM" for about the same purpose: in order to offer "INT13" support, it issues real mode DOS interupt13 disk management calls which are then executed by the VDM. By specifying the "/!BIOS" parameter you turn off that support (which for the most part is not necessary as DANIS506.ADD has other and better means to query the same info).


Yes, these started VDMs have nothing to do with seamless or even fullscreen DOS application sessions.


Pete

  • Hero Member
  • *****
  • Thank You
  • -Given: 1
  • -Receive: 28
  • Posts: 669
    • View Profile
Re: dead "VDM" entry in process list
« Reply #5 on: May 15, 2018, 02:35:03 pm »
Hi Lars

While I guess you could be right about Panorama that is not the case here as I am using SNAP.

I do not use danis506.add either.

I guess that the vdm is started by the kernel.


Regards

Pete



OS4User

  • Full Member
  • ***
  • Thank You
  • -Given: 11
  • -Receive: 6
  • Posts: 156
    • View Profile
Re: dead "VDM" entry in process list
« Reply #6 on: May 15, 2018, 02:40:29 pm »
I am using SNAP.

SNAP also creates that kind of VDM  as well as Panorama.

oemhlp.bpd also creates this VDM.
« Last Edit: May 15, 2018, 02:49:40 pm by OS4User »

Valery Sedletski

  • Full Member
  • ***
  • Thank You
  • -Given: 0
  • -Receive: 11
  • Posts: 171
    • View Profile
Re: dead "VDM" entry in process list
« Reply #7 on: May 16, 2018, 03:19:47 am »
BTW, miniVDM is not really necessary to run BIOS interrupts. X.org uses x86emu library to emulate real mode code, and thus, avoids to use VM86 mode. This even works on non-intel hardware and video cards with usual Video BIOS.

Lars

  • Sr. Member
  • ****
  • Thank You
  • -Given: 0
  • -Receive: 28
  • Posts: 253
    • View Profile
Re: dead "VDM" entry in process list
« Reply #8 on: May 16, 2018, 03:24:14 pm »
In theory, a PnP BIOS should also offer a 16-bit protected mode entry point as the minimum (and even an optional 32-bit entry point).
The problem (as so often) seems to be that about no manufacturer properly implements or tests it.

Legacy BIOS is a dead horse. It's all too late by now. And I guess nobody will have the time to rewrite the exsting drivers to use some x86emu library. And how exactly does the x86emu library work ?

Valery Sedletski

  • Full Member
  • ***
  • Thank You
  • -Given: 0
  • -Receive: 11
  • Posts: 171
    • View Profile
Re: dead "VDM" entry in process list
« Reply #9 on: May 28, 2018, 03:22:50 am »
Lars:

> Legacy BIOS is a dead horse. It's all too late by now. And I guess nobody will have the time to rewrite the exsting drivers to use some x86emu library. And how exactly does the x86emu library work ?

No need to rewrite a complete driver. Only VESA BIOS calls should be executed in x86emu library, instead of a miniVDM. x86emu just emulates 16-bit real-mode instructions. It's a full emulation of realmode x86 instructions, you just provide the callbacks for the emulator implementing interrupt handlers, memory read/write operations etc. The library works on different CPU architectures, not only x86. Intel instructions are just emulated. And it's a very small library indeed.