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
.PNVIOCGET
PNVIOCSET
PNVIOCGETNUMGE
EINVAL
]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 |