RealView Debugger Command Line Reference Guide: 2.3.138. TRACEDATAACCESS

2.3.138. TRACEDATAACCESS

Sets a trace point on data accesses, that is, either reads or writes.

Note

This command is valid only for ETM-based hardware targets.

Syntax

TRACEDATAACCESS [,qualifier...] {address | address-range}

where:

qualifier: Is an ordered list of zero or more qualifiers. The possible qualifiers are described in List of qualifiers.
address: Specifies the address at which the tracepoint is placed.
address-range: Specifies the address range for the tracepoint.

Description

This command sets a tracepoint at the address or address range you specify that triggers when an instruction access at the indicated address accesses data from memory.

The tracepoint type is by default to trigger, that is, start collecting trace information into the trace buffer. You can modify the action using the hw_out: qualifier to, for example, stop tracing.

List of qualifiers

The command qualifiers are as follows, but not all qualifiers are available for all of the supported trace targets:

hw_ahigh:(n)

Specifies the high address for an address-range tracepoint. The low address is specified by the standard tracepoint address.

For example, to set a tracepoint that triggers when any data value is accessed at an address in the range 0x1000-0x1200, enter the command:

TRACEDATAACCESS,hw_ahigh:0x1200 0x1000

hw_and:{id | "then-id"}

Perform an and or an and-then conjunction with an existing tracepoint identified by id, which is one of:

next for the next breakpoint specified for this connection
prev for the last breakpoint specified for this connection
the breakpoint list index of an existing breakpoint.

The parentheses are optional.

Tracepoints set in this way are called chained tracepoints. How RealView Debugger processes the tracepoints depends on the conjunction you have used:

In the and form, the conditions associated with both tracepoints are chained together, so that trace capture starts only when both conditions simultaneously match.
For example:
```
TRACEDATAACCESS,hw_and:next \MODIFY\#582
TRACEDATAACCESS,hw_and:prev \ACCESS\#379
```
In the and-then form, RealView Debugger examines the chained tracepoints starting with the last one you specified. When the condition for the last tracepoint is met, the previous tracepoint is enabled. However, trace capture starts only when this tracepoint condition is met. RealView Debugger continues processing all tracepoints in the chain, until the condition in first one you specified is met. At this point, trace capture starts.
Note
You must include the quotes when using the and-then form.
For example, you might have three tracepoints in a chain:
TRACEDATAACCESS,hw_and:"then-next" 0x10014 TRACEDATAACCESS,hw_and:"then-prev" 0x10018 TRACEDATAACCESS,hw_and:"then-prev" 0x1001B
In this case, RealView Debugger first checks for a data access at address 0x1001B, then at address 0x10018, and finally at address 0x10014. When all conditions are met, trace capture starts.

If you clear a tracepoint that has the ID next, then all tracepoints in the chain are cleared.

If you clear a tracepoint that has the ID prev, then that tracepoint and the following ones are cleared. The previous breakpoints in the chain remain set.

hw_dhigh:(n)

Specifies the high data value for a data-range tracepoint. The low data value is specified by the hw_dvalue qualifier.

For example, to set a tracepoint that triggers when a data value in the range 0x00-0x18 is accessed at address 0x1000, enter the command:

TRACEDATAACCESS,hw_dvalue:0x0,hw_dhigh:0x18 0x1000

hw_dmask:(n)

Specifies the data value mask for a data-range tracepoint. The data value to which the mask is applied is specified by the hw_dvalue qualifier. The data value range is determined by masking lower order bits out of the specified data value.

For example, to set a tracepoint that triggers when a data value in the range 0x400-0x4FF is accessed at address 0x1000, enter the command:

TRACEDATAACCESS,hw_dvalue:0x400,hw_dmask:0xF00 0x1000

hw_dvalue:(n)

Specifies a data value to be compared to values transmitted on the processor data bus.

For example, to set a tracepoint that triggers when the data value 0x400 is accessed at address 0x1FA00, enter the command:

TRACEDATAACCESS,hw_dvalue:0x400 0x1FA00

hw_in:{s}

Input trigger tests. The string s is specific to the trace connection being used. For the ARM ETM, the following case-sensitive forms are available:

Ignore Security Level=Yes|No

Enables Secure World and Normal World data comparisons for processors that implement the TrustZone technology:

Yes

Match when the processor is in any mode. This is the default.

No

Match only when the processor is in the mode specified by the address suffix:

S:address indicates Secure World.
N:address indicates Normal World.

For example, to capture trace when a data value is accessed at the Secure World address 0x8100, enter the command:

TRACEDATAACCESS,hw_in:{Ignore Security Level=No} S:0x8100.

"Size of Data Access=s"

This determines the following:

for data accesses, the size of the data transfer
for instruction accesses, the size of the instruction accessed.

The size s is one of:

Any

Depends on the implementation:

halfword for Thumb code
word for ARM code.

This is the default.

Halfword

16-bit accesses (Thumb code).

Word

32-bit accesses (ARM code).

For example, to set a tracepoint that triggers for any 32-bit data read or a write that occurs at an address in the range 0x1E000-0x1FF00:

TRACEDATAACCESS,hw_in:"Size of Data Access=Word" 0x1E00..0x1FF00

hw_not:{s}

Use this qualifier to invert the sense of an address, data, or hw_and term specified in the same command. The argument s can be set to:

addr: Invert the tracepoint address value.
data: Invert the tracepoint value.
then: Invert an associated hw_and:{then} condition.

For example, to set a tracepoint that triggers when a data value does not match a mask, enter the command:

TRACEDATAACCESS,hw_not:data,hw_dmask:0x00FF ...

The trace commands require an address value, and the addr variant of hw_not uses this address. For example, to trace execution at addresses other than the range 0x10040-0x10060, that is, exclude this region from the trace, enter the command:

TRACEDATAACCESS,hw_not:addr 0x10040..0x10060

The hw_not:then variant of the command is used in conjunction with hw_and to form or and nand-then conditions.

hw_out:{s}

Output trigger tests. The string s is specific to the trace connection being used. For the ARM ETM, the following case-sensitive form is defined:

"Tracepoint Type=s"

Specify the trace action that occurs when data is accessed by an instruction at the specified address, where s is:

Trigger: Output a trigger event to the TPA.
Start Tracing: Start trace capture.
Stop Tracing: Stop trace capture.
Trace Instr: Trace instructions only.
Trace Instr and Data: Trace instructions and data.

Note

An address range can be specified only for Trace Instr and Trace Instr and Data.

For example, to trace only instructions when a data read or write occurs and an instruction is executed at an address in the range 0x1E000-0x1FF00, enter the command:

TRACEDATAACCESS,hw_out:"Tracepoint Type=Trace Instr" 0x1E00..0x1FF00

hw_passcount:(n)

Specifies the number of times that the specified condition has to occur to trigger the tracepoint.

You can use this option to set up and use the ARM ETM counter hardware, if the ETM has counters and there is one available for use. ETM counters are 32 bits.

modify:(n)

Instead of creating a new tracepoint, modify the tracepoint with tracepoint ID number n by replacing the address expression and the qualifiers of the existing tracepoint to those specified in this command.

Note

You cannot use this qualifier with the hw_and qualifier to change a non-chained tracepoint to a chained tracepoint. However, you can modify a chained tracepoint with any other qualifier and also change the address expression.

Examples

The following examples show how to use TRACEDATAACCESS:

TRACEDATAACCESS &@trace\\num_runs: Trigger trace output when the variable num_runs is accessed in the file trace.c.
TRACEDATAACCESS,hw_out:"Tracepoint Type=Trace Instr" 0x8100..0x8110: Start tracing instructions when a data access occurs at an address in the range 0x8100-0x8110.
TRACEDATAACCESS,hw_pass:5,hw_out:"Tracepoint Type=Start Tracing" 0x8100: Start tracing when a data access occurs at address 0x8100.
TRACEDATAACCESS,hw_out:"Tracepoint Type=Stop Tracing" 0x8100..0x8110: Stop tracing when a data access occurs at an address in the range 0x8100-0x8110.

Alias

TRCDACCES is an alias of TRACEDATAACCESS.

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2.3.138. TRACEDATAACCESS

Note

Syntax

Description

List of qualifiers

Note

Note

Note

Examples

Alias

See also