epia m vga + memcpy failed

Peter Stuge stuge-linuxbios at cdy.org
Tue Sep 7 21:52:01 CEST 2004

On Tue, Sep 07, 2004 at 08:15:47PM -0400, Trellix78 at aol.com wrote:
> That message is from the original freebios.  I was thinking that
> shadowing is not corretly set up and that maybe the
> segment is write-protected.  After setting up shadowing,
> the chipset my turn on write protection by default, anyway.  I
> don't know how to turn write protection off specifically for the
> C00000 segment.  So far, the only reference that I can find about
> write protection is in the Pentium developer's manual. It says to
> have bit 16 of CR0 be zero to turn off write protection.

That's controlled by the descriptor table flags for the particular
descriptor in use. (cs/ds/es)

Trying to write to protected memory would cause a page fault that
LB probably doesn't recover from. (Are PF:s handled at all?)


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