Subject: Re: XF86 wsfb driver and wscons ioctl
To: David Young <firstname.lastname@example.org>
From: Michael <email@example.com>
Date: 01/18/2005 06:18:38
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> It's a shame to rule-out so many VGA adapters. ISTR that on i386,
> is a 64K window at 0xA0000 that you can slide over the video memory by
> either calling the VESA BIOS, or by writing registers on the VGA chip.
> Can't we use the existing VM machinery to trap accesses to video
> that aren't under the window, move the window, and then restart
> process made the access? In this way you win support for a large
> of framebuffers.
Hmm, I seem to remember that there was some sort of standard for PCI
VGA devices which also included some hints about BAR assignment and
therefore linear framebuffer memory - I'm pretty sure it's the only BAR
labeled prefetchable on almost(?) all VGAs and almost(?) always the
first one. With this all we need is a way to switch to whatever
resolution at 8 bit, map the framebuffer and that's it.
Is there any PCI VGA without a BAR for linear framebuffer memory? The
vast majority should have one.
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