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> OS Construction > Setting vesa from pm. |
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Artlav
In general, the question is how to enable any vesa graphic mode from pm without using 16bit interrupts. Is it possible and how?
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08 Jan 2005, 16:27 |
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ASHLEY4
Even the supped PM support, is in 16bit PM and i do not know any one who has got it working, i switch back to realmode from pm in my OS, it works fine.
here a link to some example code: http://board.flatassembler.net/topic.php?t=1854 \\\\||//// (@@) ASHLEY4. Batteries not included, Some assembly required. |
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08 Jan 2005, 16:57 |
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Artlav
The problem is that applications is not allowed to go to rm in my os...
Any options exept rm and vm86? How is it done in Xwindows? |
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08 Jan 2005, 17:35 |
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f0dder
Switch back to RM, use vm86, or code a driver for each an every card
 . VM86 is probably the best option.
Ashley, I thought the VESA PM interface was 32bit? :/ |
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08 Jan 2005, 17:49 |
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ASHLEY4
f0dder, that what it is suppost to be (a 32bit PM interface), but to use it you need to switch to a 16PM.
Its a long time since, i try to code vesa from pmode in this way, so i may be wrong. \\\\||//// (@@) ASHLEY4. Batteries not included, Some assembly required. |
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08 Jan 2005, 19:22 |
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f0dder
Hm, I seem to recall something about "get protected mode interface" which would give you a pointer and amount of bytes to copy... but I might be wrong and it might be a 16bit PM interface and it was only for bank switching iirc and it probably requires ring0 and... etc
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08 Jan 2005, 20:02 |
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f0dder
Ok, I had a look at the VBE2 specs. You have to get some info from RM, set up descriptors and proper memory and port access. However, the only functions supported are:
Quote:
...which IMHO makes the pmode interface pretty useless. So RM switch or V86 it is |
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08 Jan 2005, 20:10 |
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ASHLEY4
Your right f0dder
, i came to the same conclusion, switch back and forth works great for me, for mode switching.
But would not use it for floppy access etc though. PS: I have a vesa mode switching from pmode demo, if any ones interested, if i can get it on the site, keep getting a error on uploading  .
\\\\||//// (@@) ASHLEY4. Batteries not included, Some assembly required. |
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08 Jan 2005, 21:59 |
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f0dder
Switching back to RM works for a lot of situations. I'll rather head for the V86 model - I'm not going to add graphics support until my kernel is (a lot) more mature than it is now, and graphics support isn't that high on my wishlist anyway. And furthermore, V86 could turn out to be useful + fun + fustrating
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08 Jan 2005, 22:49 |
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