.TH RD 1 "September 20, 2005"
.SH NAME
rd, rm\- Register manipulation commands
.SH SYNOPSIS
rd [[c [n]]|d|u]
.LP
rm \fIregister-name\fP \fInew-contents\fP
.LP
ef <address>
.SH DESCRIPTION
The
.B rd
command is used to display the contents of processor and coprocessor 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.
If the bt* or pid commands have been used to change the current process then
.B rd
and
.B rm
may not be able to display any registers.
'n' argument is only used for XScale platform to identify the desired
coprocessor number, while 'd' option is not valid for XScale platform.
.P
On IA32 and IA64, 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.
.P
On XScale, 'c' argument is used to display the
all coprocessor control registers or specified coprocessor registers by
argumnet 'n'. Argument 'u' is used to display the
registers for the current task as of the last time the current task
entered the kernel. Argument 'd' is not supported.
.P
On ix86, the
.B rm
command allows modification of a register.  The following
register names are valid:  \fB%eax\fP, \fB%ebx\fP, \fB%ecx\fP,
\fB%edx\fP, \fB%esi\fP, \fB%edi\fP, \fB%esp\fP, \fB%eip\fP,
and \fB%ebp\fP.   Note that if two '%' symbols are used
consecutively, the register set displayed by the 'u' argument
to the \fBrd\fP command is modified.
.P
The debug registers, \fBdr0\fP through \fBdr3\fP and both
\fBdr6\fP and \fBdr7\fP can also be modified with the \fBrm\fP
command.
.P
On sparc64, the valid registers are named \fB%g0\fP through
\fB%g7\fP, \fB%l0\fP through \fB%l7\fP, \fB%o0\fP through
\fB%o7\fP, and \fB%i0\fP through \fB%i7\fP, with the exceptions
that \fB%o6\fP is called \fB%sp\fP and that \fB%i6\fP is called
\fB%fp\fP. The registers \fB%tstate\fP, \fB%tpc\fP, \fB%tnpc\fP,
\fB%y\fP, and \fB%fprs\fP provide state information at the time
the system entered kdb. Additionally, when viewing registers, two
convenience names are provided: \fB%&regs\fP shows the
address on the stack of the current registers, and \fB%csp\fP
shows the current stack pointer within kdb itself.
.P
While on XScale, both the cpu registers and most coprocessor
registers can be be modified. \fIregister-name\fP can be followings like
r0, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11, r12, r13, r14,
r15, cpsr to address  cpu registers. For the coprocessor registers in XSacle,
either alias name or \fICpcc[CRndd[CRmbb[Opaa]]]\fP can be used to address
the register in coprocessor cc with CRn=dd, CRm=bb and opcode2=aa. All aa, bb, cc, dd can be
1 or 2 decimal digitals, the default value is 0 when any of them is omitted. Name
acc0_h and acc0_l are used to identify the high byte and
low word of accumulator in coprocessor 0.
.P
On IA64, the parameter to
.B rd
can be d (debug registers), u (user registers at most recent entry to kernel),
i (interrupt registers), %isr (current interrupt status), s (stacked
registers), k (kernel registers).  You can also specify these individual
registers -
psr,
ifs,
ip,
unat,
pfs,
rsc,
rnat,
bsps,
pr,
ldrs,
ccv,
fpsr,
b0,
b6,
b7,
r1,
r2,
r3,
r8,
r9,
r10,
r11,
r12,
r13,
r14,
r15,
r16,
r17,
r18,
r19,
r20,
r21,
r22,
r23,
r24,
r25,
r26,
r27,
r28,
r29,
r30,
r31.
.B rm
can change any of the individual registers or the stacked registers.
.P
The
.B ef
command displays an exception frame at the specified address.
.SH LIMITATIONS
Currently the \fBrm\fP command will not allow modification of the
control registers.
.P
Currently neither the \fBrd\fP command nor the \fBrm\fP command will
display or modify the model specific registers on the Pentium
and Pentium Pro families.
.SH ENVIRONMENT
None.
.SH SMP CONSIDERATIONS
None.
.SH EXAMPLES
.TP 8
rd
Display general register set from kdb's current task.

.TP 8
rd c 0
Display coprocessor 0 registers.

.TP 8
rm %eax 0
Set the contents of \fB%eax\fP to zero.  This will be the
value of %eax when kdb returns from the condition which
invoked it.

.TP 8
rm %%eax 0
Set the value of the \fB%eax\fP register to zero.  This will
be the value the user-mode application will see upon returning
from the kernel.

.TP 8
rm %acc0_h 0
Set the contents of high byte of accumulator to zero.

.TP 8
rm dr0 0xc1287220
Set the value of the \fBdr0\fB register to \f(CW0xc1287220\fP.

.TP 8
rm %InVLD_BTB 0
Write 0 to coprocessor 15 register with CRn=7, CRm=5, opcode2=6.

.TP 8
rm %CP15CRn7CRm5Op6 0
Same with above.