| NVRAM(4) | Device Drivers Manual (prep) | NVRAM(4) | 
nvram —
#include <machine/nvram.h>
/dev/nvram is an interface to the PReP NVRAM,
  including the Global Environment Area. This interface is highly stylized;
  ioctls are used for all operations. These ioctls refer to individual variables
  in the Global Environment Area and their values.
The calls that take and/or return a variable use a pointer to an
    int variable for this purpose; others use a pointer
    to an struct pnviocdesc descriptor, which contains a
    variable and two counted strings. The first string comprises the fields
    pnv_namelen (an int) and
    pnv_name (a char *), giving
    the name of a field. The second string comprises the fields
    pnv_buflen and pnv_buf, used
    analogously. These two counted strings work in a
    “value-result” fashion. At entry to the ioctl, the counts are
    expected to reflect the buffer size; on return, the counts are updated to
    reflect the buffer contents.
The following ioctls are supported:
NULL is passed as the variable name, the first
      variable name will be returned. If the last variable is given as an
      argument, the ioctl will return EINVAL.PNVIOCGETPNVIOCSETPNVIOCGETNUMGEEINVAL]PowerPC Reference Platform Specification Version 1.1, Section 5.5
nvram itself, these
  functions run at elevated priority and may adversely affect system
  performance.
PNVIOCSET is not currently supported,
    making the nvram driver read-only at this time.
| March 1, 2007 | NetBSD 9.4 |