c_set

MIPS处理器的bootloader,龙芯就是用的修改过的PMON2

The set Command
set

The set command sets and displays environment variables.

Format

The format for this command is:

	set [name [value]]
	set nvram [cmdlist]

where:

name	is the name of the environment variable to set.

value	is the string to which the environment variable is set.

nvram	causes the environment 
variables and stty settings to be copied into NVRAM.

cmdlist	is the list of  PROM Monitor commands to be executed 
following reset.  

Entering the set command with no arguments displays all the current 
environment variables.

Functional Description

The set command is used to set or display environment variable values, to 
copy the settings of environment variables and terminal options to 
NVRAM, and to specify a list of commands to be executed by the PROM 
Monitor following reset.  

In some cases, when the Monitor displays a
variable's current value, the Monitor prints a
list of allowed values enclosed in square brackets; in other cases, no
list is shown. In general, when the value is a numeric value, or when
the value has an unlimited range of possible values, no list is shown.

The set command does not evaluate the specified value or check the 
specified value against a list of allowed values. Value checking is only 
performed when a command uses a variable. 

To set a variable to a multiple-word value, enclose the value in single or 
double quotation marks.  

When used with the nvram option, the set command copies the current
settings of the environments variables and the terminal options as
specified in the stty command into NVRAM. The optional command list
permits the user to specify  PROM Monitor
commands that will be executed following reset.  This option requires
that the flash memories support sector erase.  

To avoid reading the NVRAM during power-up, hold the console return 
key down while releasing reset. After repeating this process several times, 
you will see the following message:

Skip NVRAM read? (y/n)? 
 

If you type `y', the booting process will proceed without reading the 
NVRAM.  

Examples illustrating the use of the set command follow.

	PMON set	Display all current values.
	    brkcmd = "l @pc 1"
	    datasz = -b          [-b -h -w]
	   inalpha = hex         [hex symbol]
	    inbase = 16          [auto 8 10 16]
	    moresz = 10        
	  regstyle = sw          [hw sw]
	    rptcmd = trace       [off on trace]
	   trabort = ^K        
	     uleof = %         
	      ulcr = off         [off on]
	   validpc = "_ftext etext"
	   heaptop = 80020000  
	    dlecho = off         [off on lfeed]
	   dlproto = EtxAck      [none XonXoff EtxAck]
	  hostport = tty1      
	    prompt = "PMON "
	 etheraddr = aa:bb:cc:00:00:00
	    ipaddr = 71.0.0.211
	      diag = 0           [N[:dev]]

	PMON set moresz	Display current moresz.
	moresz = 10 

	PMON set moresz 20	Set moresz to 20 decimal.

Display current value of Cause Register and display all 
general-purpose registers: 

	PMON set brkcmd "l @epc 1;r cause;r"

Environment Variables and Default Values 

Environment VariableDefault ValueOptions

brkcmd
 
"l @epc 1"
 
command list

datasz
 
-b
 
[-b|-h|-w]

dlecho
 
off
 
[off|on|lfeed]

dlproto
 
EtxAck
 
[none|XonXoff|EtxAck]

etheraddr
 
aa:bb:cc:00:00:00
 
string

ipaddr
 
71.0.0.211
 
string

heaptop
 
80020000
 
string

hostport
 
tty1
 
tty0-9

inalpha
 
hex
 
hex symbol

inbase 
 
16
 
[auto|8|10|16]

moresz
 
10
 
0-n

prompt
 
"PMON "
 
string

regstyle
 
sw
 
[hw|sw]

rptcmd
 
trace
 
[off|on|trace]

trabort
 
^K
 
char

ulcr
 
off
 
[off|on]

uleof
 
off
 
string

validpc
 
"_ftext etext"
 
string

diag
 
0
 
[N[:dev]]

Environment variables can be set and displayed using the 
set command.

Brief descriptions of each of the variables follow, together 
with references to their complete descriptions.