Is there a way switch to real mode or V86 mode in Cosmos?

Topics: Developing Cosmos (Working on Cosmos source code directly), Using Cosmos (Developing your own OS, projects, etc), X#
Developer
Nov 6, 2012 at 6:09 PM

As far as i can see the VBE Bios is needed cuz there is not proper documentation for Video Cards.

Coordinator
Nov 6, 2012 at 6:16 PM

For basic graphics support one can look at standard VGA or the Linux X11 drivers...

Op 6 nov. 2012 20:09 schreef "forest201" <notifications@codeplex.com> het volgende:

From: forest201

As far as i can see the VBE Bios is needed cuz there is not proper documentation for Video Cards.

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Developer
Nov 6, 2012 at 6:30 PM

VBE 3.0 needs a Copy of the BIOS in a buffer. Does Cosmos already provide it?

Coordinator
Nov 6, 2012 at 6:33 PM

Cosmos doesn't. We don't want it as it needs to switch to virtual8086 mode. That mode was the reason if the frequent freezes of windows 95/98. Best thing to do is implement real hardware drivers. It's only 3-4 different major chips...

Op 6 nov. 2012 20:30 schreef "forest201" <notifications@codeplex.com> het volgende:

From: forest201

VBE 3.0 needs a Copy of the BIOS in a buffer. Does Cosmos already provide it?

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Developer
Nov 6, 2012 at 7:34 PM
Edited Nov 6, 2012 at 7:35 PM

I mean before cosmos goes in Protected Mode, It should save a copy of the BIOS at some memory location. VBE 3.0 doesn't use bios interrupts. It uses the memory address stored in Copy of BIOS to link to the Video Card. The BIOS stores the address of the video card and some other  usefully stuff needed to identify supported vga modes. With VBE 3.0 there is no need for INT 10h ,  v86 mode or real mode. No switching is done. its sort of like writing to VGA registers.

Technically it was made for 32 bit protected Mode.

Coordinator
Nov 6, 2012 at 8:47 PM

Problem then is, that Syslinux (our boot loader, not the kernel) loads us into protected mode.

Are you trying to use the versa protected mode interface? If so, it probably wont work as most BIOS don't support it....

Op 6 nov. 2012 21:34 schreef "forest201" <notifications@codeplex.com> het volgende:

From: forest201

I mean before cosmos goes in Protected Mode, It should save a copy of the BIOS at some memory location. VBE 3.0 doesn't use bios interrupts. It uses the memory address stored in Copy of BIOS to link to the Video Card. The BIOS stores the address of the video card and some other usefully stuff needed to identify supported vga modes. With VBE 3.0 there is no need for INT 10h , v86 mode or real mode. No switching is done. its sort of like writing to VGA registers.

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Nov 6, 2012 at 9:35 PM

You can use a custom bootloader.

Coordinator
Nov 7, 2012 at 6:10 AM
sure you can, but that's a huge amount of work...


On Tue, Nov 6, 2012 at 11:35 PM, jpal <notifications@codeplex.com> wrote:

From: jpal

You can use a custom bootloader.

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Coordinator
Nov 7, 2012 at 6:13 AM
Btw, have you seen my other comment? Are you trying to use the VESA protected mode interface? It's not implemented by many cards/bioses....


On Wed, Nov 7, 2012 at 8:09 AM, Matthijs ter Woord <matthijsterwoord@gmail.com> wrote:
sure you can, but that's a huge amount of work...


On Tue, Nov 6, 2012 at 11:35 PM, jpal <notifications@codeplex.com> wrote:

From: jpal

You can use a custom bootloader.

Read the full discussion online.

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Nov 7, 2012 at 11:07 AM

Maybe you could switch back.

Developer
Nov 7, 2012 at 11:45 AM

Yes. I'm only writing it for popular  video cards like Nvidia, ATI and probably intel. We can just use VGAScreen as Generic Driver.  I also think i should just write device specific drivers but there is not much document on Programming video hardware.

Developer
Nov 7, 2012 at 11:46 AM
Edited Nov 7, 2012 at 11:48 AM

It's not that easy to switch to v86 mode in protected mode and further more it slows down the operating system! and  u need to define some variables in the bootloader as well as make a v86 handler.

Developer
Nov 7, 2012 at 11:50 AM

Then write a bootloader!

On Nov 7, 2012 5:46 AM, "forest201" <notifications@codeplex.com> wrote:

From: forest201

It's not easy as it sounds! cuz u need to define some variables in the bootloader.

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