Difference between revisions of "Power ISA/Machine State Register"

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(→‎Privilege State: reference dedicated page for this)
 
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{| class="wikitable"
+
The '''Machine State Register''', or '''MSR''', is a Branch Facility register usually defined in Book III in of the [[Power ISA|Power ISA]]. Among other uses, the MSR contains information about the privilege level the thread is running at. When referring to a setting in the Machine State Register, the code of the setting is in subscript directly after the abbreviation MSR. For example, documentation will refer to the Hypervisor State bit as MSR<sub>HV</sub>.
|+Machine State Register
+
 
 +
== Map ==
 +
 
 +
{|class="wikitable"
 +
|+Machine State Register Bits
 
!rowspan="3"|Bit
 
!rowspan="3"|Bit
 
!rowspan="3"|Code
 
!rowspan="3"|Code
Line 16: Line 20:
 
|Sixty-Four-Bit Mode
 
|Sixty-Four-Bit Mode
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
 
!1:2
 
!1:2
|
+
|colspan="2"|Reserved
|Reserved
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
|
 
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|-
 
|-
Line 30: Line 33:
 
|Hypervisor State
 
|Hypervisor State
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
 
!4
 
!4
|
+
|colspan="2"|Reserved
|Reserved
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
|
 
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|-
 
|-
Line 44: Line 46:
 
|Split Little Endian
 
|Split Little Endian
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
|style="background:#FF9;vertical-align:middle;text-align:center;"|Yes<ref group="note">Power version ISA 3.0B defines this bit as something set in hardware to be zero, and warns against changing it.</ref>
+
|style="background:#FF9;vertical-align:middle;text-align:center;"|Yes<ref group="note">Power ISA version 3.0B defines this bit as something set in hardware to be zero, and warns against changing it.</ref>
 
|-
 
|-
 
!6:28
 
!6:28
|
+
|colspan="2"|Reserved
|Reserved
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
|
 
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|-
 
|-
Line 58: Line 59:
 
|Transaction State
 
|Transaction State
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
Line 65: Line 66:
 
|Transactional Memory Available
 
|Transactional Memory Available
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 +
|-
 +
!32
 +
|CM
 +
|Computation Mode
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|-
 +
!33
 +
|colspan="2"|Reserved
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|-
 +
!34
 +
|colspan="2"|Implementation-dependant
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|style="background:#99F;vertical-align:middle;text-align:center;"|Yes
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|-
 +
!35
 +
|GS
 +
|Guest State
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|-
 
|-
!32:37
+
!36
|
+
|colspan="2"|Implementation-dependant
|Reserved
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|style="background:#99F;vertical-align:middle;text-align:center;"|Yes
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|-
 +
!37
 +
|UCLE
 +
|User Cache Locking Enable
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
|
+
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|-
 
|-
Line 79: Line 112:
 
|Vector Available
 
|Vector Available
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#FF9;vertical-align:middle;text-align:center;"|Yes<ref group="note">Power ISA version 2.07 Book III-E defines this as ''SPV'' - ''SP/Embedded Floating-Point/Vector Available''</ref>
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
 
!39
 
!39
|
+
|colspan="2"|Reserved
|Reserved
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
|
 
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|-
 
|-
Line 93: Line 125:
 
|VSX Available
 
|VSX Available
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
 
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 +
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 +
|-
 +
!41
 +
|S
 +
|Secure Mode<ref name="kusakata-uv">https://doc.kusakata.com/powerpc/ultravisor.html</ref>
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|-
 +
!42:45
 +
|colspan="2"|Reserved
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|-
 +
!46
 +
|CE
 +
|Critical Enable
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|-
 
|-
!41:47
+
!47
|
+
|colspan="2"|Reserved
|Reserved
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
|
 
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|-
 
|-
Line 107: Line 158:
 
|External Interrupt Enable
 
|External Interrupt Enable
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes<ref group="note">Power ISA version 2.07 Book III-E calls this ''External Enable''</ref>
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
Line 114: Line 165:
 
|Problem State
 
|Problem State
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
Line 121: Line 172:
 
|Floating-Point Available
 
|Floating-Point Available
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
Line 128: Line 179:
 
|Machine Check Interrupt Enable
 
|Machine Check Interrupt Enable
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes<ref group="note">Power ISA version 2.07 Book III-E calls this ''Machine Check Enable''</ref>
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
Line 135: Line 186:
 
|Floating-Point Exception Mode 0
 
|Floating-Point Exception Mode 0
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
Line 142: Line 193:
 
|Single-Step Trace Enable
 
|Single-Step Trace Enable
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#99F;vertical-align:middle;text-align:center;"|Yes<ref group="note">Power ISA version 2.07 Book III-E defines this as Implementation-dependent</ref>
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes<ref group="note" name="msr_te">Power ISA version 3.0B defines bits 53 and 54 together as ''TE'' - Trace Enable - and defines having both bits set as ''reserved''</ref>
+
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes<ref group="note" name="msr_te">Power ISA version 3.0B defines bits 53 and 54 together as ''TE'' - ''Trace Enable'' - and defines having both bits set as ''reserved''</ref>
 
|-
 
|-
 
!54
 
!54
Line 149: Line 200:
 
|Branch Trace Enable
 
|Branch Trace Enable
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#FF9;vertical-align:middle;text-align:center;"|Yes<ref group="note">Power ISA version 2.07 Book III-E defines this as ''DE'' - ''Debug Interrupt Enable''</ref>
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes<ref group="note" name="msr_te"/>
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes<ref group="note" name="msr_te"/>
 
|-
 
|-
Line 156: Line 207:
 
|Floating-Point Exception Mode 1
 
|Floating-Point Exception Mode 1
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
!56:57
+
!56
|
+
|colspan="2"|Reserved
|Reserved
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 +
|-
 +
!57
 +
|colspan="2"|Reserved
 +
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
|
 
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|-
 
|-
Line 170: Line 226:
 
|Instruction Relocate
 
|Instruction Relocate
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#FF9;vertical-align:middle;text-align:center;"|Yes<ref group="note">Power ISA version 2.07 Book III-E defines this as ''IS'' - ''Instruction Address Space''</ref>
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
Line 177: Line 233:
 
|Data Relocate
 
|Data Relocate
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#FF9;vertical-align:middle;text-align:center;"|Yes<ref group="note">Power ISA version 2.07 Book III-E defines this as ''DS'' - ''Data Address Space''</ref>
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
 
!60
 
!60
 
|
 
|
|Reserved
+
|Implementation-dependant
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
|
+
|style="background:#99F;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|-
 
|-
Line 191: Line 247:
 
|Performance Monitor Mark
 
|Performance Monitor Mark
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
Line 198: Line 254:
 
|Recoverable Interrupt
 
|Recoverable Interrupt
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|-
 
|-
Line 205: Line 261:
 
|Little-Endian Mode
 
|Little-Endian Mode
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
|
+
|style="background:#F99;vertical-align:middle;text-align:center;"|No
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|style="background:#9F9;vertical-align:middle;text-align:center;"|Yes
 
|}
 
|}
  
 
<references group="note"/>
 
<references group="note"/>
 +
 +
== List ==
 +
 +
=== Bit 0 - Sixty-Four-Bit Mode (SF) ===
 +
 +
{|class="wikitable"
 +
!0
 +
|The thread is in 32-bit mode
 +
|-
 +
!1
 +
|The thread is in 64-bit mode
 +
|}
 +
 +
=== Bit 3 - Hypervisor State (HV) ===
 +
 +
{|class="wikitable"
 +
!0
 +
|The thread is not in hypervisor state
 +
|-
 +
!1
 +
|The thread is in hypervisor state '''if''' MSR<sub>PR</sub> = 0
 +
|}
 +
 +
=== Bit 5 ===
 +
 +
==== Split Little Endian (SLE) ====
 +
 +
{|class="wikitable"
 +
!0
 +
|Instruction and data storage use the same endian-ness
 +
|-
 +
!1
 +
|Instruction storage accesses use the value specified by MSR<sub>LE</sub>. Data storage accesses use the opposite.
 +
|}
 +
 +
==== Power ISA version 3 ====
 +
 +
Power ISA version 3 does not define bit 5 so much as warn that, "software must ensure that this bit contains 0". It then reassure that the hardware will initialise it to 0.
 +
 +
=== Bit 49 - Problem State (PR) ===
 +
 +
{|class="wikitable"
 +
!0
 +
|The thread is in a privileged state
 +
|-
 +
!1
 +
|The thread is in problem state
 +
|}
 +
 +
=== Bit 63 - Little-Endian Mode (LE) ===
 +
 +
{|class="wikitable"
 +
!0
 +
|The thread is in Big-Endian mode
 +
|-
 +
!1
 +
|The thread is in Little-Endian mode.
 +
|}
 +
 +
== Multi-bit States ==
 +
 +
=== Privilege State ===
 +
 +
<div role="note" class="hatnote navigation-not-searchable">Main page: [[Power ISA/Privilege States]]</div>
 +
 +
The privilege state of a thread is a property of multiple bits in the MSR; however, not all of these states are available on all Power processors; for example, the Ultravisor state was first officially announced for [[POWER9|POWER9's]] DD2.3 stepping. Additionally, at time of release the official ISA documentation still does not fully describe the Ultravisor state.<ref name="kusakata-uv"/>
 +
 +
{|class="wikitable sortable"
 +
!MSR<sub>S</sub>
 +
!MSR<sub>HV</sub>
 +
!MSR<sub>PR</sub>
 +
!State
 +
|-
 +
!0
 +
!0
 +
!0
 +
|Privileged
 +
|-
 +
!0
 +
!0
 +
!1
 +
|Problem
 +
|-
 +
!0
 +
!1
 +
!0
 +
|Hypervisor
 +
|-
 +
!0
 +
!1
 +
!1
 +
|Problem
 +
|-
 +
!1
 +
!0
 +
!0
 +
|Privileged
 +
|-
 +
!1
 +
!0
 +
!1
 +
|Problem
 +
|-
 +
!1
 +
!1
 +
!0
 +
|Ultravisor
 +
|-
 +
!1
 +
!1
 +
!1
 +
|Reserved
 +
|}
 +
 +
=== Endian-ness ===
 +
 +
{|class="wikitable"
 +
!MSR<sub>SLE</sub>
 +
!MSR<sub>LE</sub>
 +
!Data
 +
!Instruction
 +
|-
 +
!0
 +
!0
 +
|Big-Endian
 +
|Big-Endian
 +
|-
 +
!0
 +
!1
 +
|Little-Endian
 +
|Little-Endian
 +
|-
 +
!1
 +
!0
 +
|Little-Endian
 +
|Big-Endian
 +
|-
 +
!1
 +
!1
 +
|Big-Endian
 +
|Little-Endian
 +
|}
 +
 +
== References ==
 +
 +
<references/>
 +
 +
[[Category:Power Architecture]]

Latest revision as of 20:57, 4 May 2020

The Machine State Register, or MSR, is a Branch Facility register usually defined in Book III in of the Power ISA. Among other uses, the MSR contains information about the privilege level the thread is running at. When referring to a setting in the Machine State Register, the code of the setting is in subscript directly after the abbreviation MSR. For example, documentation will refer to the Hypervisor State bit as MSRHV.

Map

Machine State Register Bits
Bit Code Name Defined
2.07 3.0B
III-S III-E
0 SF Sixty-Four-Bit Mode Yes No Yes
1:2 Reserved No No No
3 HV Hypervisor State Yes No Yes
4 Reserved No No No
5 SLE Split Little Endian Yes No Yes[note 1]
6:28 Reserved No No No
29:30 TS Transaction State Yes No Yes
31 TM Transactional Memory Available Yes No Yes
32 CM Computation Mode No Yes No
33 Reserved No No No
34 Implementation-dependant No Yes No
35 GS Guest State No Yes No
36 Implementation-dependant No Yes No
37 UCLE User Cache Locking Enable No Yes No
38 VEC Vector Available Yes Yes[note 2] Yes
39 Reserved No No No
40 VSX VSX Available Yes Yes Yes
41 S Secure Mode[1] No No No
42:45 Reserved No No No
46 CE Critical Enable No Yes No
47 Reserved No No No
48 EE External Interrupt Enable Yes Yes[note 3] Yes
49 PR Problem State Yes Yes Yes
50 FP Floating-Point Available Yes Yes Yes
51 ME Machine Check Interrupt Enable Yes Yes[note 4] Yes
52 FE0 Floating-Point Exception Mode 0 Yes Yes Yes
53 SE Single-Step Trace Enable Yes Yes[note 5] Yes[note 6]
54 BE Branch Trace Enable Yes Yes[note 7] Yes[note 6]
55 FE1 Floating-Point Exception Mode 1 Yes Yes Yes
56 Reserved No No No
57 Reserved No No No
58 IR Instruction Relocate Yes Yes[note 8] Yes
59 DR Data Relocate Yes Yes[note 9] Yes
60 Implementation-dependant No Yes No
61 PMM Performance Monitor Mark Yes Yes Yes
62 RI Recoverable Interrupt Yes No Yes
63 LE Little-Endian Mode Yes No Yes
  1. Power ISA version 3.0B defines this bit as something set in hardware to be zero, and warns against changing it.
  2. Power ISA version 2.07 Book III-E defines this as SPV - SP/Embedded Floating-Point/Vector Available
  3. Power ISA version 2.07 Book III-E calls this External Enable
  4. Power ISA version 2.07 Book III-E calls this Machine Check Enable
  5. Power ISA version 2.07 Book III-E defines this as Implementation-dependent
  6. 6.0 6.1 Power ISA version 3.0B defines bits 53 and 54 together as TE - Trace Enable - and defines having both bits set as reserved
  7. Power ISA version 2.07 Book III-E defines this as DE - Debug Interrupt Enable
  8. Power ISA version 2.07 Book III-E defines this as IS - Instruction Address Space
  9. Power ISA version 2.07 Book III-E defines this as DS - Data Address Space

List

Bit 0 - Sixty-Four-Bit Mode (SF)

0 The thread is in 32-bit mode
1 The thread is in 64-bit mode

Bit 3 - Hypervisor State (HV)

0 The thread is not in hypervisor state
1 The thread is in hypervisor state if MSRPR = 0

Bit 5

Split Little Endian (SLE)

0 Instruction and data storage use the same endian-ness
1 Instruction storage accesses use the value specified by MSRLE. Data storage accesses use the opposite.

Power ISA version 3

Power ISA version 3 does not define bit 5 so much as warn that, "software must ensure that this bit contains 0". It then reassure that the hardware will initialise it to 0.

Bit 49 - Problem State (PR)

0 The thread is in a privileged state
1 The thread is in problem state

Bit 63 - Little-Endian Mode (LE)

0 The thread is in Big-Endian mode
1 The thread is in Little-Endian mode.

Multi-bit States

Privilege State

The privilege state of a thread is a property of multiple bits in the MSR; however, not all of these states are available on all Power processors; for example, the Ultravisor state was first officially announced for POWER9's DD2.3 stepping. Additionally, at time of release the official ISA documentation still does not fully describe the Ultravisor state.[1]

MSRS MSRHV MSRPR State
0 0 0 Privileged
0 0 1 Problem
0 1 0 Hypervisor
0 1 1 Problem
1 0 0 Privileged
1 0 1 Problem
1 1 0 Ultravisor
1 1 1 Reserved

Endian-ness

MSRSLE MSRLE Data Instruction
0 0 Big-Endian Big-Endian
0 1 Little-Endian Little-Endian
1 0 Little-Endian Big-Endian
1 1 Big-Endian Little-Endian

References