Intel
82801BA ICH2 Datasheet
9-77
LPC Interface Bridge Registers (D31:F0)
10
Hub Interface SMI Status (HUBSMI_STS)
—R/WC.
1 = ICH2 received an SMI message via the hub interface. The software must read the memory
controller hub (or its equivalent) to determine the reason for the SMI#.
0 = Software clears this bit by writing a 1 to the bit position.
9
Hub Interface SCI Status (HUBSCI_STS)
—R/WC.
1 = ICH2 received an SCI message via the hub interface. The software must read the memory
controller hub (or its equivalent) to determine the reason for the SCI.
0 = Software clears this bit by writing a 1 to the bit position.
8
BIOS Write Status (BIOSWR_STS)
—R/WC.
1 = ICH2 sets this bit and generates and SMI# to indicate an illegal attempt to write to the BIOS.
This occurs when either:
a) The BIOSWP bit is changed from 0 to 1 and the BLD bit is also set, or
b) any write is attempted to the BIOS and the BIOSWP bit is also set.
0 = Software clears this bit by writing a 1 to the bit position.
Note:On write cycles attempted to the 4 MB lower alias to the BIOS space, the BIOSWR_STS will
not be set.
7
New Century Status (NEWCENTURY_STS)
—R/WC.
This bit is in the RTC well.
1 = This bit is set when the Year byte (RTC I/O space, index offset 09h) rolls over from 99 to 00.
Setting this bit will cause an SMI# (but not a wake event).
0 = Cleared by writing a 1 to the bit position or by RTCRST# going active.
Note that the NEWCENTURY_STS bit is not valid when the RTC battery is first installed (or when
RTC power has not been maintained). Software can determine if RTC power has not been
maintained by checking the RTC_PWR_STS bit or by other means (e.g., a checksum on RTC
RAM). If RTC power is determined to have not been maintained, BIOS should set the time to a
legal value and then clear the NEWCENTURY_STS bit.
The NEWCENTURY_STS bit may take up to 3 RTC clocks for the bit to be cleared after a “1” is
written to the bit to clear it. After writing a “1” to this bit, software should not exit the SMI handler
until verifying that the bit has actually been cleared. This will ensure that the SMI is not re-entered.
6:4
Reserved
3
Time Out Status (TIMEOUT)
—R/WC.
1 = Set by ICH2 to indicate that the SMI was caused by the TCO timer reaching 0.
0 = Software clears this bit by writing a 1 to the bit position.
2
TCO Interrupt Status (TCO_INT_STS)
—R/WC.
1 = SMI handler caused the interrupt by writing to the TCO_DAT_OUT register.
0 = Software clears this bit by writing a 1 to the bit position.
1
Software TCO SMI Status (SW_TCO_SMI)
—R/WC.
1 = Software caused an SMI# by writing to the TCO_DAT_IN register.
0 = Software clears this bit by writing a 1 to the bit position.
0
NMI to SMI Status (NMI2SMI_STS)
—RO.
1 = Set by the ICH2 when an SMI# occurs because an event occurred that would otherwise have
caused an NMI (because NMI2SMI_EN is set).
0 = Cleared by clearing the associated NMI status bit.
Bit
Description
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