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.TH "MTRR_ADD_PAGE" "" "06 October 2005" "" ""

.SH NAME
mtrr_add_page \- Add a memory type region
.SH SYNOPSIS
"SYNOPSIS"
.sp
\fB
.sp
int mtrr_add_page  (unsigned long \fIbase\fB, unsigned long \fIsize\fB, unsigned int \fItype\fB, char \fIincrement\fB);
\fR
.SH "ARGUMENTS"
.TP
\fB\fIbase\fB\fR
Physical base address of region in pages (4 KB)
.TP
\fB\fIsize\fB\fR
Physical size of region in pages (4 KB)
.TP
\fB\fItype\fB\fR
Type of MTRR desired
.TP
\fB\fIincrement\fB\fR
If this is true do usage counting on the region
.SH "DESCRIPTION"
.PP
Memory type region registers control the caching on newer Intel and
non Intel processors. This function allows drivers to request an
MTRR is added. The details and hardware specifics of each processor's
implementation are hidden from the caller, but nevertheless the 
caller should expect to need to provide a power of two size on an
equivalent power of two boundary.
.PP
If the region cannot be added either because all regions are in use
or the CPU cannot support it a negative value is returned. On success
the register number for this entry is returned, but should be treated
as a cookie only.
.PP
On a multiprocessor machine the changes are made to all processors.
This is required on x86 by the Intel processors.
.PP
The available types are
.PP
MTRR_TYPE_UNCACHABLE - No caching
.PP
MTRR_TYPE_WRBACK - Write data back in bursts whenever
.PP
MTRR_TYPE_WRCOMB - Write data back soon but allow bursts
.PP
MTRR_TYPE_WRTHROUGH - Cache reads but not writes
.SH "BUGS"
.PP
Needs a quiet flag for the cases where drivers do not mind
failures and do not wish system log messages to be sent.