
162
Registers
Chapter 4
AMD-8111 HyperTransport I/O Hub Data Sheet
24674
Rev. 3.00
April 2003
AMD Preliminary Information
BIOS Access Control Registers
DevB:0x80, DevB:0x84, and DevB:0x88
Default:
0000 0000h (for each).
Attribute:
Read-write.
These registers consists of 24 4-bit registers called OAR (open at reset) locks. Each 4-bit register
applies to a sector of the BIOS in the 5 megabyte BIOS range at the top of the 4-gigabyte address
space as follows:
DevB:0x84 and DevB:0x80 contain 16 four-bit lock registers, called OARx where x ranges across
[F:0]; each four-bit register controls a 64Kbyte address range at the top megabyte of memory as
follows: [FFFx_FFFFh:FFFx_0000h].
DevB:0x88 contains 8 four-bit lock registers, called OARx where x ranges as [E, C, A, 8, 6, 4, 2,
0]; each four-bit register controls an 8Kbyte address range as follows:
[FFBF_(x+1)FFFh:FFBF_x000h].
Accesses to BIOS space in the low megabyte (between 000C_0000h and 000F_FFFFh) are mapped to
the top megabyte (between FFFC_0000h and FFFF_FFFFh) on the LPC bus; the OAR locks for these
apply to these accesses based on the remapped address at the top megabyte. Note: there is an
additional OAR lock specified in DevB:0x8C. Note: OAR locks only apply to BIOS address space; if
there is an access to an OAR lock address range that is not in BIOS address space as defined by
DevB:0x43, then the OAR lock register is ignored. Note: the OAR locks only apply to the BIOS
address space on the LPC bus; if DevB:3x48[PCIBIOS] = 1, then they are ignored.
As defined below, access to BIOS space can be limited to when the host is in system management
mode (SMM). HyperTransport technology system management messages are sent that specify when
the host is in SMM.
Table 48.
OARx Lock Locations
Register
DevB:0x88:
DevB:0x84:
DevB:0x80:
Bits 31:28 Bits 27:24 Bits 23:20 Bits 19:16 Bits 15:12 Bits 11:8
OARE
OARC
OARA
OARF
OARE
OARD
OAR7
OAR6
OAR5
Bits 7:4
OAR2
OAR9
OAR1
Bits 3:0
OAR0
OAR8
OAR0
OAR8
OARC
OAR4
OAR6
OARB
OAR3
OAR4
OARA
OAR2
Table 49.
OARx Lock Bit Descriptions
Bits
OARx[3]
Description
FLLOCK. Full access to RD/WRLOCK lock.
Read; write 1 only. This bit can only be set High by
software; it is cleared by RESET_L. 0=Read-write access to RDLOCK and WRLOCK enabled.
1=Write access to RDLOCK and WRLOCK disabled (whether the system is in SMM mode or not).
SLLOCK. SMM access to RD/WRLOCK lock.
Read; write 1 only. This bit can only be set High
by software; it is cleared by RESET_L. 0=Read-write access to RDLOCK and WRLOCK enabled
(if FLLOCK=0). 1=Write access to RDLOCK and WRLOCK only enabled in SMM mode (if
FLLOCK=0).
WRLOCK. BIOS sector x write lock.
Read; write if enabled by SLLOCK and FLLOCK. 0=Write
access to BIOS sector x enabled (if DevB:0x40[RWR]=1). 1=Write access to BIOS sector x
disabled.
RDLOCK. BIOS sector x read lock.
Read; write if enabled by SLLOCK and FLLOCK. 0=Read
access to BIOS sector x enabled. 1=Read access to BIOS sector x disabled.
OARx[2]
OARx[1]
OARx[0]