freebsd-dev/share/man/man4/nvram2env.4

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.Dd April 3, 2011
.Dt NVRAM2ENV 4
.Os
.Sh NAME
.Nm nvram2env
.Nd "copy nvram-like data into kernel environment"
.Sh SYNOPSIS
.Cd "device nvram2env"
.Sh DESCRIPTION
.Nm
implements a simple method of reading the NVRAM-like data and information
stored in flash and storing it in the kernel environment.
It can then be used by various device drivers at boot-time.
.Pp
The NVRAM-like data is an array of zero terminated strings.
Each string contains the string name, "=" delimiter and the string value.
.Pp
.Nm
copies the environment values into kernel environment using the kernel setenv call.
.Pp
Configuration of
.Nm
is done in
.Xr device.hints 5
defining the NVRAM base address, fallback base address, maxsize and flags.
.Pp
.Nm
is currently MIPS-specific.
.Ss base
base - physical address where data block is stored.
.Ss fallbackbase
fallbackbase - physical address where data block is stored, but only
if not found at base.
.Ss maxsize
maxsize - maximum size of data block.
.Ss flags
flags - control flags, used to select nvram type and enable/disable CRC check.
.Bl -tag -width indent
.It Fa 0x0001
Avoid CRC checking.
Currently CRC checking is not implemented, so to be future
compatible, please set it to "1".
.It Fa 0x0002
Use format "Generic", skip uint32_t field, then zero terminating array of
strings.
.It Fa 0x0004
Use Broadcom CFE format, uint32_t signature "FLSH", uint32_t size,
three unused fields uint32_t, then data.
.It Fa 0x0008
Use U-Boot format, uint32_t crc, then zero terminating array of strings.
.El
.Sh EXAMPLES
Usage in U-Boot case:
.Bd -literal -offset indent
hint.nvram.0.base=0x1f030000
hint.nvram.0.maxsize=0x2000
hint.nvram.0.flags=3 # 1 = No check, 2 = Format Generic
hint.nvram.1.base=0x1f032000
hint.nvram.1.maxsize=0x4000
hint.nvram.1.flags=3 # 1 = No check, 2 = Format Generic
.Ed
.Pp
CFE nvram with fallback:
.Bd -literal -offset indent
hint.nvram.0.base=0x1fff8000
hint.nvram.0.fallbackbase=0x1fc00400
hint.nvram.0.flags=4 # 4 = Format Broadcom
.Ed
.Pp
but seems for CFE nvram preferred to read both blocks:
.Pp
NVRAM partition: Static, CFE internal
.Bd -literal -offset indent
hint.nvram.0.flags=0x05 # Broadcom + nocheck
hint.nvram.0.base=0x1fc00400
.Ed
.Pp
Dynamic, editable form CFE, override values from first
.Bd -literal -offset indent
hint.nvram.1.flags=0x05 # Broadcom + nocheck
hint.nvram.1.base=0x1cff8000
.Ed
.Sh SEE ALSO
.Xr kenv 1 ,
.Xr kenv 2
.Sh HISTORY
.Nm
first appeared in
.Fx 9.0 .
.Sh AUTHORS
.An Aleksandr Rybalko Aq Mt ray@ddteam.net