t (Trace)

t[a|c|n|s|x|z][=start_addr][count][addr]
 

The t command executes one or more instructions along with the default command string and then displays the decoded instruction. If you include the start_addr parameter, tracing starts at the specified address. Otherwise, the command steps through the next machine instruction and then executes the default command string. The t command uses the hardware trace mode of the Intel microprocessor. Consequently, you can also trace instructions stored in read-only memory (ROM).

a

Indicates that an ending address is specified for the trace. Instructions are traced until the address in addr is reached.

c

Suppresses all output and counts instructions traced. An ending address is required for this command. Instructions are traced until the address in addr is reached.

n

Suppresses the register display so just the assembly line is displayed. This works only if the default command, zd, is set to r (the normal setting).

s

Suppresses output; the instruction and count are displayed for each call and the return from that call.

x

Forces the debugger to trace regions of code known to be untraceable (_PGSwitchContext, for example).

z

Allows original trap handler address to be traced into without having to unhook the exception. Use this option instead of vcp d; t; vsp d.

start_addr

Specifies the instruction address at which to start tracing. The equal sign (=) is required.

count

Specifies the number of instructions to execute and trace.

addr

Specifies the instruction address at which to stop tracing.

The following command causes the debugger to execute 16 (10h) instructions beginning at 011A in the current selector:

t=011A 10
 

The debugger executes and displays the results of the default command string for each instruction. The display is scrolled until the last instruction is executed. Press the CTRL+S key combination to stop the scrolling and CTRL+Q to resume.

This command does not trace into INTs (but will trace out), and tracing through popf or popfd usually does not work.