kdb_rd(3)

NAME

rd, rm- Register manipulation commands

SYNOPSIS

rd [c|d|u]

rm register-name new-contents

ef <address>

DESCRIPTION

The rd command is used to display the contents of processor registers. Without any arguments, the rd command displays the contents of the general register set at the point at which the kernel debugger was entered.

With the 'c' argument, the processor control registers %cr0, %cr1, %cr2 and %cr4 are displayed, while with the 'd' argument the processor debug registers are displayed. If the 'u' argument is supplied, the registers for the current task as of the last time the current task entered the kernel are displayed.

On ix86, the rm command allows modification of a register. The following register names are valid: %eax, %ebx, %ecx, %edx, %esi, %edi, %esp, %eip, and %ebp. Note that if two '%' symbols are used consecutively, the register set displayed by the 'u' argument to the rd command is modified.

The debug registers, dr0 through dr3 and both dr6 and dr7 can also be modified with the rm command.

On sparc64, the valid registers are named %g0 through %g7, %l0 through %l7, %o0 through %o7, and %i0 through %i7, with the exceptions that %o6 is called %sp and that %i6 is called %fp. The registers %tstate, %tpc, %tnpc, %y, and %fprs provide state information at the time the system entered kdb. Additionally, when viewing registers, two convenience names are provided: %&regs shows the address on the stack of the current registers, and %csp shows the current stack pointer within kdb itself.

The ef command displays an exception frame at the specified address.

LIMITATIONS

Currently the rm command will not allow modification of the control registers.

Currently neither the rd command nor the rm command will display or modify the model specific registers on the Pentium and Pentium Pro families.

ENVIRONMENT

None.

SMP CONSIDERATIONS

None.

EXAMPLES

rd

Display general register set.

rm %eax 0

Set the contents of %eax to zero. This will be the value of %eax when kdb returns from the condition which invoked it.

rm %%eax 0

Set the value of the %eax register to zero. This will be the value the user-mode application will see upon returning from the kernel.

rm dr0 0xc1287220

Set the value of the dr0 register to 0xc1287220.