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Virtualization / Re: Win-OS/2 - Open vbesvga.drv video driver
« on: June 22, 2025, 12:35:33 am »
One thing I discovered was that the X VESA driver failed on a UEFI install, to quote myself.
Developer answered,
So possibly the fact that the VGA BIOS is at a non-standard location on a UEFI install.
I also discovered that the changes that were made to SNAP broke the X VESA driver subtly, namely system hung when returning to the PM from X.
Another interesting discovery when reviewing the X source code was that X actually uses the SNAP code for its mini-VDM.
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So out of curiosity, I tried opening a VESA xsession on a UEFI install. It failed, this seems to be the problem,
...
(EE) VESA(0): V_BIOS address 0x98000 out of range
...
On a BIOS install, it succeeds with,
...
(II) VESA(0): Primary V_BIOS segment is: 0xc000
Developer answered,
Code: [Select]
BIOS at C000 can only be emulated in VDM. XFree86 definitely uses a
mini-VDM that lacks any functionality. "VGA BIOS" at 9xxx is an emulation
for system boot time and for panorama/gengradd.
So possibly the fact that the VGA BIOS is at a non-standard location on a UEFI install.
I also discovered that the changes that were made to SNAP broke the X VESA driver subtly, namely system hung when returning to the PM from X.
Another interesting discovery when reviewing the X source code was that X actually uses the SNAP code for its mini-VDM.