Intel BX80605X3430 Data Sheet - Page 39

Datasheet, Volume 1

39

Power Management

4.2.3

Requesting Low-Power Idle States

The primary software interfaces for requesting low-power idle states are through the

MWAIT instruction with sub-state hints and the HLT instruction (for C1 and C1E).

However, software may make C-state requests using the legacy method of I/O reads

from the ACPI-defined processor clock control registers, referred to as P_LVLx. This

method of requesting C-states provides legacy support for operating systems that

initiate C-state transitions using I/O reads.

For legacy operating systems, P_LVLx I/O reads are converted within the processor to

the equivalent MWAIT C-state request. Therefore, P_LVLx reads do not directly result in

I/O reads to the system. The feature, known as I/O MWAIT redirection, must be

enabled in the BIOS.

Note:

The P_LVLx I/O Monitor address needs to be set up before using the P_LVLx I/O read

interface. Each P-LVLx is mapped to the supported MWAIT(Cx) instruction as follows:

The BIOS can write to the C-state range field of the PMG_IO_CAPTURE MSR to restrict

the range of I/O addresses that are trapped and emulate MWAIT like functionality. Any

P_LVLx reads outside of this range does not cause an I/O redirection to MWAIT(Cx) like

request. They fall through like a normal I/O instruction.

Note:

When P_LVLx I/O instructions are used, MWAIT substates cannot be defined. The

MWAIT substate is always zero if I/O MWAIT redirection is used. By default, P_LVLx I/O

redirections enable the MWAIT 'break on EFLAGS.IF' feature that triggers a wakeup on

an interrupt, even if interrupts are masked by EFLAGS.IF.

4.2.4

Core C-states

The following are general rules for all core C-states, unless specified otherwise:

•

A core C-State is determined by the lowest numerical thread state (such that,

Thread 0 requests C1E while thread1 requests C3, resulting in a core C1E state).

See

Table 4-3

.

•

A core transitions to C0 state when:

—

an interrupt occurs.

—

there is an access to the monitored address if the state was entered using an

MWAIT instruction.

•

For core C1/C1E, and core C3, an interrupt directed toward a single thread wakes

only that thread. However, since both threads are no longer at the same core C-

state, the core resolves to C0.

•

For core C6, an interrupt coming into either thread wakes both threads into C0

state.

•

Any interrupt coming into the processor package may wake any core.

Table 4-4.

P_LVLx to MWAIT Conversion

P_LVLx

MWAIT(Cx)

Notes

P_LVL2

MWAIT(C3)

P_LVL3

MWAIT(C6)

C6. No sub-states allowed

Section	Page
1 Introduction	9
1.1 Processor Feature Details	11
1.1.1 Supported Technologies	11
1.2 Interfaces	11
1.2.1 System Memory Support	11
1.2.2 PCI Express*	12
1.2.3 Direct Media Interface (DMI)	13
1.2.4 Platform Environment Control Interface (PECI)	14
1.3 Power Management Support	14
1.3.1 Processor Core	14
1.3.2 System	14
1.3.3 Memory Controller	14
1.3.4 PCI Express*	14
1.4 Thermal Management Support	15
1.5 Package	15
1.6 Terminology	15
1.7 Related Documents	17
2 Interfaces	19
2.1 System Memory Interface	19
2.1.1 System Memory Technology Supported	19
2.1.2 System Memory Timing Support	21
2.1.3 System Memory Organization Modes	21
2.1.3.1 Single-Channel Mode	21
2.1.3.2 Dual-Channel Mode—Intel® Flex Memory Technology Mode	22
2.1.4 Rules for Populating Memory Slots	23
2.1.5 Technology Enhancements of Intel® Fast Memory Access (Intel® FMA)	24
2.1.5.1 Just-in-Time Command Scheduling	24
2.1.5.2 Command Overlap	24
2.1.5.3 Out-of-Order Scheduling	24
2.1.6 System Memory Pre-Charge Power Down Support Details	24
2.2 PCI Express* Interface	25
2.2.1 PCI Express* Architecture	25
2.2.1.1 Transaction Layer	26
2.2.1.2 Data Link Layer	26
2.2.1.3 Physical Layer	26
2.2.2 PCI Express* Configuration Mechanism	27
2.2.3 PCI Express* Ports and Bifurcation	28
2.2.3.1 PCI Express* Bifurcated Mode	28
2.3 Direct Media Interface (DMI)	28
2.3.1 DMI Error Flow	28
2.3.2 Processor/PCH Compatibility Assumptions	28
2.3.3 DMI Link Down	28
2.4 Platform Environment Control Interface (PECI)	29
2.5 Interface Clocking	29
2.5.1 Internal Clocking Requirements	29
3 Technologies	31
3.1 Intel® Virtualization Technology	31
3.1.1 Intel® VT-x Objectives	31
3.1.2 Intel® VT-x Features	31
3.1.3 Intel® VT-d Objectives	32
3.1.4 Intel® VT-d Features	32
3.1.5 Intel® VT-d Features Not Supported	33
3.2 Intel® Trusted Execution Technology (Intel® TXT)	33
3.3 Intel® Hyper-Threading Technology	34
3.4 Intel® Turbo Boost Technology	34
4 Power Management	35
4.1 ACPI States Supported	35
4.1.1 System States	35
4.1.2 Processor Core/Package Idle States	35
4.1.3 Integrated Memory Controller States	35
4.1.4 PCI Express* Link States	36
4.1.5 Interface State Combinations	36
4.2 Processor Core Power Management	36
4.2.1 Enhanced Intel® SpeedStep® Technology	37
4.2.2 Low-Power Idle States	37
4.2.3 Requesting Low-Power Idle States	39
4.2.4 Core C-states	39
4.2.4.1 Core C0 State	40
4.2.4.2 Core C1/C1E State	40
4.2.4.3 Core C3 State	40
4.2.4.4 Core C6 State	40
4.2.4.5 C-State Auto-Demotion	40
4.2.5 Package C-States	41
4.2.5.1 Package C0	42
4.2.5.2 Package C1/C1E	42
4.2.5.3 Package C3 State	43
4.2.5.4 Package C6 State	43
4.3 IMC Power Management	43
4.3.1 Disabling Unused System Memory Outputs	43
4.3.2 DRAM Power Management and Initialization	44
4.3.2.1 Initialization Role of CKE	44
4.3.2.2 Conditional Self-Refresh	44
4.3.2.3 Dynamic Power Down Operation	44
4.3.2.4 DRAM I/O Power Management	45
4.4 PCI Express* Power Management	45
5 Thermal Management	47
6 Signal Description	49
6.1 System Memory Interface	50
6.2 Memory Reference and Compensation	52
6.3 Reset and Miscellaneous Signals	52
6.4 PCI Express* Based Interface Signals	53
6.5 DMI—Processor to PCH Serial Interface	53
6.6 PLL Signals	54
6.7 Intel® Flexible Display Interface Signals	54
6.8 JTAG/ITP Signals	55
6.9 Error and Thermal Protection	56
6.10 Power Sequencing	57
6.11 Processor Core Power Signals	57
6.12 Graphics and Memory Core Power Signals	59
6.13 Ground and NCTF	60
6.14 Processor Internal Pull Up/Pull Down	60
7 Electrical Specifications	61
7.1 Power and Ground Lands	61
7.2 Decoupling Guidelines	61
7.2.1 Voltage Rail Decoupling	61
7.3 Processor Clocking (BCLK[0], BCLK#[0])	62
7.3.1 PLL Power Supply	62
7.4 VCC Voltage Identification (VID)	62
7.5 Reserved or Unused Signals	66
7.6 Signal Groups	66
7.7 Test Access Port (TAP) Connection	69
7.8 Absolute Maximum and Minimum Ratings	69
7.9 DC Specifications	70
7.9.1 Voltage and Current Specifications	70
7.10 Platform Environmental Control Interface (PECI) DC Specifications	77
7.10.1 DC Characteristics	77
7.10.2 Input Device Hysteresis	78
8 Processor Land and Signal Information	79

Intel BX80605X3430 Data Sheet - Page 39

Requesting Low-Power Idle States, Core C-states

Page 39 highlights