ddi_btop(9F) Kernel Functions for Drivers ddi_btop(9F)
NAME
ddi_btop, ddi_btopr, ddi_ptob - page size conversions
SYNOPSIS
#include <sys/ddi.h>
#include <sys/sunddi.h>
unsigned long ddi_btop(dev_info_t *dip, unsigned long bytes);
unsigned long ddi_btopr(dev_info_t *dip, unsigned long bytes);
unsigned long ddi_ptob(dev_info_t *dip, unsigned long pages);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI).
DESCRIPTION
This set of routines use the parent nexus driver to perform conversions in page size units.
ddi_btop() converts the given number of bytes to the number of memory pages that it corresponds to, rounding down in the case that the byte
count is not a page multiple.
ddi_btopr() converts the given number of bytes to the number of memory pages that it corresponds to, rounding up in the case that the byte
count is not a page multiple.
ddi_ptob() converts the given number of pages to the number of bytes that it corresponds to.
Because bus nexus may possess their own hardware address translation facilities, these routines should be used in preference to the corre-
sponding DDI/DKI routines btop(9F), btopr(9F), and ptob(9F), which only deal in terms of the pagesize of the main system MMU.
RETURN VALUES
ddi_btop() and ddi_btopr() return the number of corresponding pages. ddi_ptob() returns the corresponding number of bytes. There are no
error return values.
CONTEXT
This function can be called from user or interrupt context.
EXAMPLES
Example 1: Find the size (in bytes) of one page
pagesize = ddi_ptob(dip, 1L);
SEE ALSO
btop(9F), btopr(9F), ptob(9F)
Writing Device Drivers
SunOS 5.10 11 Sep 1991 ddi_btop(9F)
