.\"	$NetBSD: elanpar.4,v 1.9 2017/02/17 22:24:46 christos Exp $
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.\" Copyright (c) 2008 David Young.  All rights reserved.
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.\" Written by David Young.
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.Dd February 17, 2017
.Dt ELANPAR 4 i386
.Os
.Sh NAME
.Nm elanpar
.Nd AMD Elan SC520 Programmable Address Regions
.Sh SYNOPSIS
.Cd "elansc* at mainbus? bus ?"
.Cd "elanpar* at elansc?"
.Sh DESCRIPTION
The
.Nm
driver supports the write-protect feature of the AMD
Elan SC520 microcontroller's integrated Programmable Address Regions.
Currently,
.Nm
protects the kernel text from being overwritten by the CPU or errant DMA.
.Sh DIAGNOSTICS
.Bl -diag
.It elanpar0: cpu violated write-protect window %u
.It elanpar0: gp violated write-protect window %u
.It elanpar0: pci violated write-protect window %u
.El
.Pp
A Programmable Address Region stopped
either the CPU, the general-purpose bus
.Pq gp ,
or a PCI bus master from writing to the indicated window of
write-protected memory.
.Bl -diag
.It elanpar0: %u bytes of kernel text are unprotected
.El
.Pp
.Nm
has not write-protected
.Em %u
bytes of the kernel text.
.Sh SEE ALSO
.Xr i386/elanpex 4 ,
.Xr i386/elansc 4 ,
.Xr dmesg 8 ,
.Xr syslogd 8
.Sh HISTORY
The
.Nm
device first appeared in
.Nx 5.0 .
.Sh AUTHORS
The
.Nm
driver was written by
.An David Young Aq Mt dyoung@NetBSD.org .
.Sh BUGS
.Nm
leaves as many as 65535 bytes unprotected at the beginning and
end of kernel text.
Also,
.Nm
is not compatible with setting breakpoints
using
.Xr ddb 4 .
Disable
.Nm
using
.Ic drvctl Fl d Ar elanpar0
before setting a breakpoint with
.Xr ddb 4 .