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Re: video mem access with oskit-mach

From: Marcus Brinkmann
Subject: Re: video mem access with oskit-mach
Date: Tue, 2 Oct 2001 00:37:24 +0200
User-agent: Mutt/1.3.22i

On Mon, Oct 01, 2001 at 05:12:17PM -0400, Roland McGrath wrote:
> I believe that everything should already be in place in Mach (both flavors)
> and in the Hurd for mapping physical device memory such as the frame buffer.
> mmap on /dev/mem ought to dtrt already.  If not, it's a bug.
> The only reason to have a more specific device for this is security,
> e.g. /dev/vga that can mmap only a constrained range.  We can do this by
> Hurdish means if we ever care to.  Theoretically one could use a remap
> store on top of /dev/mem, whos runs give mostly holes and only map the
> address ranges you want to allow for the frame buffer.

Yes, this is much better than frobbing mach devices directly.
I include a patch for colortext below, maybe somebody wants to try that.
There is another issue I didn't mention... colortext pokes io ports
to set the cursor position.  There is a bug report against gnumach which
allows all tasks to write to io ports.  If I read oskit/x86/main.c
correctly, requesting access to ioports is not implemented yet, but
will it allow all accesses like GNU Mach or none at all?


`Rhubarb is no Egyptian god.' Debian http://www.debian.org brinkmd@debian.org
Marcus Brinkmann              GNU    http://www.gnu.org    marcus@gnu.org

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