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From: plippone AT lk-hp-16 DOT hut DOT fi (Petri Lipponen)
Newsgroups: comp.os.msdos.djgpp
Subject: HOHow to access VBE2.0 linear frame buffer?
Date: 7 Nov 95 23:57:10 GMT
Organization: Helsinki University of Technology, CS lab
Lines: 32
Distribution: world
Nntp-Posting-Host: lk-hp-16.hut.fi
Keywords: linear,VBE2.0,GPF
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Dj-Gateway: from newsgroup comp.os.msdos.djgpp

Hi.

So far I've been able to do get_VESA_mode_info call and (using UniVBE2.0)
found out that the linear frame buffer is at 0xf0000000. The problem is
that both DJGPP v1.12 and v2.0b3 deny any access to those addresses. I've
tried to use _farsetsel(_dos_ds) and _farpokeb() calls, to find out what
the 0xf0000000 physical is in linear address (__dpmi_get_physical_mapping()
gave 0 ) and to use mprotect(ADDR,2048*1024,PROT_WRITE) to that address (and
to 0xf0000000). Nothing works. Without mprotect, accessing to 0xf0000000 
gives GPF and with it, machine reboots.

I'm completely out of what to do, so if any of you has knowledge
to help me, please do.

Thanks in advance...

Petri Lipponen

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	Name: Petri Lipponen	email: plippone AT snakemail DOT hut DOT fi	
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	Name: Petri Lipponen	email: plippone AT snakemail DOT hut DOT fi	
	Addr: Jamerantaival 11 k 222 Espoo 02150 FINLAND
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