186 AMD Geode™ LX Processors Data Book
CPU Core Register Descriptions
33234H
5.5.2.93 Real Time Stamp Counter MSR (RTSC_MSR)
5.5.2.94 TSC and RTSC Low DWORDs MSR (RTSC_TSC_MSR)
MSR Address 00001910h
Type R/W
Reset Value 00000000_00000000h
RTSC_MSR Register Map
63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32
RTSC (High DWORD)
313029282726252423222120191817161514131211109876543210
RTSC (Low DWORD)
RTSC_MSR Bit Descriptions
Bit Name Description
63:0 RTSC Real Time Stamp Counter. This register is the 64-bit secondary, or “real” time stamp
counter. This counter allows software to configure the TSC not to include SMM or DMM
time, and still have an accurate real time measurement that includes these times.
BC_CONFIG0_MSR (MSR 00001900h) contains configuration bits that determine if the
RTSC counts during Suspend mode. It always counts during SMM and DMM modes.
All bits in this register are writable, unlike the TSC that clears the upper DWORD to 0 on
writes.
MSR Address 00001911h
Type RO
Reset Value 00000000_00000000h
RTSC_TSC_MSR Register Map
63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32
RTSC_LOW
313029282726252423222120191817161514131211109876543210
TSC_LOW
RTSC_TSC_MSR Bit Descriptions
Bit Name Description
63:32 RTSC_LOW Real Time Stamp Counter Low DWORD. This field provides a synchronized snapshot
of the low DWORD of the RTSC register (MSR 00001910h).
31:0 TSC_LOW Time Stamp Counter Low DWORD. This field provides a synchronized snapshot of the
low DWORD of the TSC register (MSR 00000010h).