FUJITSU Implementation Supplement Fujitsu SPARC64 V User Manual
Page 32
Release 1.0, 1 July 2002
F. Chapter 5
Registers
21
The Performance Control Register in SPARC64 V is illustrated in
and
FIGURE 5-1
SPARC64 V Performance Control Register (PCR) (ASR 16)
TABLE 5-2
PCR
Bit Description
Bit
Field
Description
47:32
OVF
Overflow Clear/Set/Status. Used to read counter overflow status (via
RDPCR
) and clear
or set counter overflow status bits (via
WRPCR
).
PCR.OVF
is a SPARC64 V-specific field
(impl. dep. #207).
The following figure depicts the bit layout of SPARC64 V
OVF
field for four counter
pairs. Counter status bits are cleared on write of 0 to the appropriate
OVF
bit.
26
OVRO
Overflow read-only. Write-only/read-as-zero field specifying
PCR.OVF
update behavior
for
WRPCR.PCR.
The
OVRO
field is implementation -dependent (impl. dep. #207).
WRPCR.PCR
with
PCR.OVRO = 1
inhibits updating of
PCR.OVF
for the current write
only. The intention of
PCR.OVRO
is to write
PCR
while preserving current
PCR.OVF
value.
PCR.OVF
is maintained internally by hardware, so a subsequent
RDPCR.PCR
returns accurate overflow status at the time.
24:22
NC
Number of counter pairs. Three-bit, read-only field specifying the number of counter
pairs, encoded as 0–7 for 1–8 counter pairs (impl. dep. #207).
For SPARC64 V, the hardcoded value of
NC
is 3 (indicating presence of 4 counter pairs).
20:18
SC
Select
PIC
. In SPARC64 V, three-bit field specifying which counter pair is currently
selected as
PIC
(ASR 17) and which
SU
/
SL
values are visible to software. On write,
PCR.SC
selects which counter pair is updated (unless
PCR.ULRO
is set; see below). On
read,
PCR.SC
selects which counter pair is to be read through
PIC
(ASR 17).
16:11
SU
Defined (as
S1
) in SPARC JPS1 Commonality.
9:4
SL
Defined (as
S0
) in SPARC JPS1 Commonality.
3
ULRO
Implementation-dependent field (impl. dep. #207) that specifies whether
SU
/
SL
are
read-only. In SPARC64 V, this field is write-only/read-as-zero, specifying update
behavior of
SU
/
SL
on write. When
PCR.ULRO
=
1
,
SU
/
SL
are considered as read-only;
the values set on
PCR.SU/PCR.SL
are not written into
SU/SL
. When
PCR.ULRO
=
0
,
SU/SL
are updated.
PCR.ULRO
is intended to switch visible
PIC
by writing
PCR.SC
,
without affecting current selection of
SU/SL
of that
PIC
. On
PCR
read,
PCR.SU/PCR.SL
always shows the current setting of the
PIC
regardless of
PCR.ULRO
.
2
UT
Defined in SPARC JPS1 Commonality.
1
ST
Defined in SPARC JPS1 Commonality.
63
16
10 9
4
0
OVF
0
SL
SU
0
SC
17
18
21
0
NC
22
24
0
OVRO
26
27
31
32
0
47
48
0
25
ULRO UT ST PRIV
1
2
3
11
20
15
L0
U0
L1
U1
0
0
1
2
3
4
5
6
7
L2
U2
L3
U3