UBootCmdGroupMemory < DULG

%SECTION0{name=UBootCmdMemory}% Memory Commands

%SECTION1{name=UBootCmdBase}% base    - print or set address offset

%INCLUDE{DULGData_%BOARD%.UBootBaseHelp}%

You can use the =base= command (short: =ba=) to print or set a "base
address" that is used as the address offset for all subsequent memory commands; the
default value of the base address is 0, so all addresses you enter are
used unmodified.  However, when you repeatedly have to access a
certain memory region (like the internal memory of some embedded
[[PowerPC][Power Architecture]]® processors) it can be very convenient to set the base address
to the start of this area and then use only the offsets:

%INCLUDE{DULGData_%BOARD%.UBootBase}%

%SECTION1{name=UBootCmdCrc}% crc32   - checksum calculation

The =crc32= command (short: =crc=)
can be used to calculate a CRC32 checksum over a range of memory:

%INCLUDE{DULGData_%BOARD%.UBootCrc}%

When used with 3 arguments, the command stores the calculated
checksum at the given address:

%INCLUDE{DULGData_%BOARD%.UBootCrcStore}%

As you can see, the CRC32 checksum was not only printed, but also
stored at address 0x100000.

%SECTION1{name=UBootCmdCmp}% cmp     - memory compare

%INCLUDE{DULGData_%BOARD%.UBootCmpHelp}%

With the =cmp= command you can test whether the contents
of two memory areas are identical or not. The command will test either
the whole area as specified by the 3rd (length) argument, or stop at
the first difference.

%INCLUDE{DULGData_%BOARD%.UBootCmp}%

Like most memory commands the =cmp= can access the
memory in different sizes: as 32 bit (long word), 16 bit (word) or 8
bit (byte) data. If invoked just as =cmp= the
default size (32 bit or long words) is used; the same can be selected
explicitly by typing =cmp.l= instead. If you want
to access memory as 16 bit or word data, you can use the variant
=cmp.w= instead; and to access memory as 8 bit or
byte data please use =cmp.b=.

%X% Please note that the _count_ argument specifies
the number of data items to process, i. e. the number of long words or
words or bytes to compare.

%INCLUDE{DULGData_%BOARD%.UBootCmpExt}%

%SECTION1{name=UBootCmdCp}% cp      - memory copy

%INCLUDE{DULGData_%BOARD%.UBootCpHelp}%

The =cp= command is used to copy memory areas.

%INCLUDE{DULGData_%BOARD%.UBootCp}%

The =cp= command understands the type extensions
=.l=, =.w= and
=.b= :

%INCLUDE{DULGData_%BOARD%.UBootCpExt}%

%SECTION1{name=UBootCmdMd}% md      - memory display

%INCLUDE{DULGData_%BOARD%.UBootMdHelp}%

The =md= command can be used to display memory contents both
as hexadecimal and ASCII data.

%INCLUDE{DULGData_%BOARD%.UBootMd}%

This command can also be used with the type extensions
=.l=, =.w= and
=.b= :

%INCLUDE{DULGData_%BOARD%.UBootMdExt}%

The last displayed memory address and the value of the count argument
are remembered, so when you enter =md= again
_without arguments_ it will automatically
continue at the next address, and use the same count again.

%INCLUDE{DULGData_%BOARD%.UBootMdLength}%

%SECTION1{name=UBootCmdMm}% mm      - memory modify (auto-incrementing)

%INCLUDE{DULGData_%BOARD%.UBootMmHelp}%

The =mm= command is a method to interactively modify memory
contents. It will display the address and current contents and then
prompt for user input. If you enter a legal hexadecimal number, this
new value will be written to the address. Then the next address will
be prompted. If you don't enter any value and just press ENTER, then
the contents of this address will remain unchanged. The command stops
as soon as you enter any data that is not a hex number (like
=.=):

%INCLUDE{DULGData_%BOARD%.UBootMm}%

Again this command can be used with the type extensions
=.l=, =.w= and
=.b= :

%INCLUDE{DULGData_%BOARD%.UBootMmW}%

%INCLUDE{DULGData_%BOARD%.UBootMmB}%

%SECTION1{name=UBootCmdMtest}% mtest   - simple RAM test

%INCLUDE{DULGData_%BOARD%.UBootMtestHelp}%

The =mtest= provides a <emphasis>simple</emphasis>
memory test.

%INCLUDE{DULGData_%BOARD%.UBootMtest}%

%X% This tests writes to memory, thus modifying the memory
contents. It will fail when applied to ROM or flash memory.

%X% This command may crash the system when the tested memory range
includes areas that are needed for the operation of the U-Boot
firmware (like exception vector code, or U-Boot's internal program
code, stack or heap memory areas).

%SECTION1{name=UBootCmdMw}% mw      - memory write (fill)

%INCLUDE{DULGData_%BOARD%.UBootMwHelp}%

The =mw= command is a way to initialize (fill) memory with
some value. When called without a <emphasis>count</emphasis>
argument, the value will be written only to the specified address.
When used with a <emphasis>count</emphasis> value, the entire memory
area will be initialized with this value:

%INCLUDE{DULGData_%BOARD%.UBootMw}%

This is another command that accepts the type extensions
=.l=, =.w= and
=.b= :

%INCLUDE{DULGData_%BOARD%.UBootMwExt}%

%SECTION1{name=UBootCmdNm}% nm      - memory modify (constant address)

%INCLUDE{DULGData_%BOARD%.UBootNmHelp}%

The =nm= command (<emphasis>non-incrementing memory
modify</emphasis>) can be used to interactively write different data
several times to the same address. This can be useful for instance to
access and modify device registers:

%INCLUDE{DULGData_%BOARD%.UBootNm}%

The =nm= command also accepts the type
extensions =.l=, =.w= and
=.b=.

%SECTION1{name=UBootCmdLoop}% loop    - infinite loop on address range

%INCLUDE{DULGData_%BOARD%.UBootLoopHelp}%

The =loop= command reads in a tight loop from a
range of memory. This is intended as a special form of a memory test,
since this command tries to read the memory as fast as possible.

%X% This command will never terminate.
There is no way to stop it but to reset the board!

<pre>
%UBOOT_PROMPT% loop 100000 8
</pre>
5.9.1. Information Commands		1. Abstract		5.9.3. Flash Memory Commands
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