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Status Display Parameters

As specified in the previous section, each node can take a Parameters attribute. The parameters specified here will be used by the StatusDisplay class of the BUTool, to infer which status table we want to register the node to, row and column names for this node, and so forth. A full set of possible parameters are shown in the table below:

Parameter keys Required Description
Status Required Status uHAL parameter. Integer display priority 1=always display
Show Optional Show uHAL parameter. "nz" to suppress zero values, "z" to suppress non-zero values (see note below)
Table Required Table uHAL parameter. Name of table for status display
Row Required Row uHAL parameter. Name of row in table for status display
Column Required Column uHAL parameter. Name of column in table for status display
Format Optional Format uHAL parameter.

All keys are concatenated into the address table attribute parameters which is processed as a semicolon-delimited keyword=value list by uHAL. No special characters are permitted in these columns (only letters, numbers and "_"). For an item to appear in the status displays, the Status, Table, Row and Column must be specified. P_Table, P_Row and P_Column are sorted alphabetically. Leading digits and "_" characters should be stripped before display so that e.g. "0_" can be used to force a sort order.

Details on Parameters

This sub-section has information on how the parameter keys mention above can be specified, and their interpretation by the StatusDisplay class of BUTool.


The Status key sets the display priority. 0 is used to mark configuration registers which may be optionally displayed or not according to user preference. Positive integers 1-9 indicate various levels of detail for status values, with value 1 indicating the highest priority items which should always be displayed. On the other hand, value 9 indicates the lowest priority items, which will only be displayed when a call to status command is made with status level 9.

In general, if Status=N is specified for a node, it will only be displayed in BUTool calls to status M command, where M is greater or equal to N. In BUTool, M defaults to 1, so a call to status will only display the most high-priority registers (i.e. Status=1).

Row and Column Names

In the Row and Column fields, the sequence _N, where N is a digit between 1-9, results in substituting the corresponding field from the delimited id, e.g. if a field is _2 and the register ID is STATUS.AMC01.ERRORS, then the resulting value would be AMC01. It is also possible to specify multiple special sequences: Following the same example, if Row=_2_3 is specified, the resulting row name would be AMC01 ERRORS. Note that if a _N sequence is specified such that N is larger than the register value length (in this example, it is 3), BUTool will stop execution and will throw a BAD_MARKUP_NAME exception.

It is possible to specify literal underscores in the row/column names as well. This can be done in two ways:

  • Use a double underscore (i.e. '__'). For example, if Row=ROW__3 is specified, the resulting row name would be ROW_3.
  • Follow the underscore with a non-digit character. For example, if Row=USER_INFO is specified, the resulting row name would be USER_INFO, since the character following the underscore is not a digit.

To wrap it up, if we're given a register with an ID of STATUS.AMC01.ERRORS, here are some examples that display the parsing technique:

Row/Column Value Resulting Name
_4 Invalid markup, BAD_MARKUP_NAME error

Note: Please also note that, the same parsing technique described here will be applied to the Table parameter as well (i.e. the table name).


The Show parameter has several possible settings:

Value Interpretation
nz Display this value only if it is non-zero
z Display this value only if it is zero
nzr Display the entire row in the corresponding table only if this value is non-zero


This parameter will specify how the value is to be formatted and printed out in it's respective table. Below is a list of possible formats accepted by BUTool:

Format Interpretation
"x"/"X" Print number as hex
"d" Print as a signed decimal number
"u" Print as a unsigned decimal number
"t" Print bare enumerations. Enums are set by following "t" with _number1_ENUMname1_number2_ENUMname2 etc.
"T" Print enumerations along with the numerical value. Enums are defined the same way as "t"
"M"/"m" Convert from integer to floating point using the equation below
"linear11" linear11 float format
"fp16" Using ARM fp16 format
"IP" Convert 32-bit number into an IP address

The equation to convert integer to a floating point for Format="m"/"M" is as follows:

y = (sign) * (M_n/M_d) * x + (sign) * (b_n/b_d)

where the Format is specified as: Format=m_sign_Mn_Md_sign_bn_bd. sign=0 denotes a negative sign, whereas all other values indicate a positive sign.


Below, you can find some example address table entries that have several different use cases.

<!-- Unsigned integer with status level 1 -->
<node id="COUNT"    mask="0x000000FF" permission="rw" parameters="Table=ZYNQ_OS;Row=_3;Column=_4;Format=u;Status=1"/>

<!-- This value will be ONLY shown if it is non-zero -->
<node id="MINS"     mask="0x0000FF00" permission="rw" parameters="Table=ZYNQ_OS;Row=_3;Column=_4;Format=u;Status=1;Show=nz"/>

<!-- The original unsigned int value will be divided by 100 to get the CPU_LOAD -->
<node id="CPU_LOAD"  mask="0x0000FFFF" permission="rw" parameters="Table=ZYNQ_OS;Row=_3;Column=Percent;Format=m_1_1_100_1_0_1;Status=1"/>

<!-- Enumeration: A value of 0 will display INACTIVE, and 1 will display ACTIVE -->
<node id="ACTIVE"    address="0x0" mask="0x00000100" permission="r" parameters="Table=CM_UART_MON;Column=_2;Row=MON_STATE;Status=1;Format=t_0_INACTIVE_1_ACTIVE" />

64-bit Registers

By default, values from a single register can be at most 32-bits. However, for 64-bit register values, BUTool has the functionality to merge the values from two separate registers, and display a 64-bit integer.

To achieve this, two registers need to be specified: One register ID will end with _LO suffix, while the other will end with _HI. The register IDs must be identical otherwise. BUTool will handle the merging of such register values into a single 64-bit value, and display only that.

AXI FW unblocking

Adding Unblock=name to the parameters list will cause a action write to that register if a call to axiunblock is called with the matching name.

Default value

Adding default=val on a rw register will cause that register to reset/power-up-reset to that value instead of '0'.