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Memory view

Use the Memory view to display and modify the contents of memory.

This view enables you to:

  • Specify the start address for the view, either as an absolute address or as an expression, for example $pc+256. You can also specify an address held in a register by dragging and dropping the register from the Registers view into the Memory view.
  • Specify the display size of the Memory view in bytes, as an offset value from the start address.
  • Specify the format of the memory cell values. The default is hexadecimal.
  • Set the width of the memory cells in the Memory view. The default is 4 bytes.
  • Display the ASCII character equivalent of the memory values.
  • Freeze the view to prevent it from being updated by a running target.

Figure 15-22 Memory view

Memory view

The Memory view only provides the facility to modify how memory is displayed in this view. It does not enable you to change the access width for the memory region. To control the memory access width, you can use:

  • The memory command to configure access widths for a region of memory, followed by the x command to read memory according to those access widths and display the contents.
  • The memory set command to write to memory with an explicit access width.

Toolbar and context menu options

The following options are available from the toolbar or context menu:

Linked:<context>

Links this view to the selected connection in the Debug Control view. This is the default. Alternatively you can link the view to a different connection. If the connection you want is not shown in the drop-down list you might have to select it first in the Debug Control view.

History buttonhistorybtn

Addresses and expressions you specify in the Address field are added to the list, and persist until you clear the history list. If you want to keep an expression for later use, add it to the Expressions view.

Number of columnsnumcolsbtn

The options enable you to resize the number of columns shown in the Memory view.

Fit to view

Select to resize the number of columns automatically.

2, 4, 8, 16

Select the number of columns to display in the Memory view in a 2, 4, 8, or 16-column layout.

Custom

Select and specify the custom column layout you require.

To specify these values as default, set them under Window > Preferences > Arm DS > Debugger > Memory View .

Timed auto refresh timedautorefreshbtn

Use the Timed Auto-Refresh option to specify an auto-refresh of the values in the view.

Start

Starts the timed auto-refresh.

Stop

Stops the timed auto-refresh.

Update Interval

Specifies the auto refresh interval in seconds.

Update When

Specifies when to refresh the view:

Running

Refreshes the view only while the target is running.

Stopped

Refreshes the view only while the target is stopped.

Always

Always refreshes the view.

Note

When you select Running or Always, the Memory and Screen views are only updated if the target supports access to that memory when running. For example, some CoreSight targets support access to physical memory at any time through the Debug Access Port (DAP) to the Advanced High-performance Bus Access Port (AHB-AP) bridge. In those cases, add the AHB: prefix to the address selected in the Memory or Screen views. This type of access bypasses any cache on the processor core, so the memory content returned might be different to the value that the core reads.
Properties

Displays the Timed Auto-Refresh Properties dialog box where you can specify these options as default.

Formatformatbtn

Click to cycle through the memory cell formats and cell widths, or select a format from the drop-down menu. The default is hexadecimal with a display width of 4 bytes.

Use the Hide Base Prefix option to hide base prefixes where applicable.

For example:

  • For hexadecimal values, this option hides the preceding 0x. The value 0xEA000016 is shown as EA000016.
  • For binary values, this option hides the preceding 0b. The value 0b00010110 is shown as 00010110.
  • For octal values, this option hides the preceding 0. The value 035200000026 is shown as 35200000026.
Searchsearchbtn

Searches through debug information for symbols.

Details paneldetailspanelbtn

Show or hide the details panel, which displays the value of the selected memory cell in different formats. Memory view with details panel

Figure 15-23 Memory view with details panel

Memory view with details panel

Address field

Enter the address where you want to start viewing the target memory. Alternatively, you can enter an expression that evaluates to an address.

Addresses and expressions you specify are added to the drop-down history list, and persist until you clear the view history. If you want to keep an expression for later use, add it to the Expressions view.

Size field

The number of bytes to display.

View Menu

The following View Menu options are available:

New Memory View

Displays a new instance of the Memory view.

Show Tooltips

Toggles the display of tooltips on memory cell values.

Auto Alignment

Aligns the memory view to the currently selected data width.

Show Compressed Addresses

Shows the least significant bytes of the address that are not repeating.

Show Cache

Shows how the core views the memory from the perspective of the different caches on the target. This is disabled by default. When showing cache, the view is auto-aligned to the cache-line size. When showing cache, the memory view shows a column for each cache. If populated, the cache columns display the state of each cache using the Modified/Owned/Exclusive/Shared/Invalid(MOESI) cache coherency protocol notation.

Click on a cache column header or select a cache from the Cache Data menu to display the data as viewed from that cache. The Memory (non-cached) option from the Cache Data menu shows the data in memory, as if all caches are disabled.

Figure 15-24 Memory view with Show Cache option enabled

Memory view with Show Cache option enabled

Note

In multiprocessor systems, it is common to have caches dedicated to particular cores. For example, a dual-core system might have per-core L1 caches, but share a single L2 cache. Cache snooping is a hardware feature that allows per-core caches to be accessed from other cores. In such cases the Cache Data field shows all the caches that are accessible to each core, whether directly or through snooping.
Byte Order

Selects the byte order of the memory. The default is Auto (LE).

Clear History

Clears the list of addresses and expressions in the History drop-down list.

Import Memory

Reads data from a file and writes it to memory.

Export Memory

Reads data from memory and writes it to a file.

Fill Memory

Writes a specific pattern of bytes to memory

Update View When Hidden

Enables the updating of the view when it is hidden behind other views. By default, this view does not update when hidden.

Refresh

Refreshes the view.

Freeze Data

Toggles the freezing of data in the current view. This option also disables or enables the Address and Size fields. You can still use the Refresh option to manually refresh the view.

Editing context menu options

The context menu of the column header enables you to toggle the display of the individual columns.

Reset Columns

Displays the default columns.

Characters

Displays the Characters column.

The following options are available on the context menu when you select a memory cell value, the Address field, or the Size field for editing:

Cut

Copies and deletes the selected value.

Copy

Copies the selected value.

Paste

Pastes a value that you have previously cut or copied into the selected memory cell or field.

Delete

Deletes the selected value.

Select All

Selects all the addresses.

The following additional options are available on the context menu when you select a memory cell value:

Toggle Watchpoint

Sets or removes a watchpoint at the selected address. After a watchpoint is set, you can:

Enable Watchpoint

If disabled, enables the watchpoint at the selected address.

Disable Watchpoint

Disables the watchpoint at the selected address.

Remove Watchpoint

Removes the watchpoint at the selected address.

Watchpoint Properties

Displays and lets you change the watchpoint properties.

Translate Address <address>

Displays the MMU view and translates the address of the selected value in memory.

Memory view default preferences

You can specify default preferences to apply to the Memory view. Specifying default options ensures that your preferences are applied across all debug connections.

To specify default options for the Memory view, set them under Window > Preferences > Arm DS > Debugger > Memory View.

Figure 15-25 Memory View preferences

Memory View preferences

Number of columns

The options enable you to resize the number of columns shown in the Memory view.

Fit to view

Select to resize the number of columns automatically.

2, 4, 8, 16

Select the number of columns to display in the Memory view in a 2, 4, 8, or 16-column layout.

Custom

Select and specify the custom column layout you require.

Data format

Specify the format of the memory cell values. The default is hexadecimal.

Data size

Set the width of the memory cells in the Memory view. The default is 4 bytes.

Hide base prefix for memory values

Select to hide the base prefix where applicable.

For example:

  • For hexadecimal values, this option hides the preceding 0x. So the value 0xEA000016 is shown as EA000016.
  • For binary values, this option hides the preceding 0b. So the value 0b00010110 is shown as 00010110.
  • For octal values, this option hides the preceding 0. So the value 035200000026 is shown as 35200000026.
Hide Characters column

Select to the hide the Characters column in the Memory view.

When this option is unselected, ASCII characters are shown in the Memory view: Show Characters column in the Memory view

Figure 15-26 Show Characters column in the Memory view

Show Characters column in the Memory view

Another way to toggle the visibility of the Characters column, is to right-click the context menu and select or unselect the Characters option: Select Characters from context menu to show theASCII characters

Figure 15-27 Select Characters from context menu to show the ASCII characters

Select Characters from context menu to show the ASCII characters

Show tooltip

Select to control the display of tooltips on memory cell values.

Automatically align the memory addresses

Aligns the memory view to the currently selected data width.

Show compressed addresses

Shows the least significant bytes of the address that are not repeating.

Show details panel

Shows the details panel, which displays the value of the selected memory cell in different formats.

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