Datasheet

Processor Configuration Registers
34 Datasheet, Volume 2
MSI Interrupts At fixed address below 4 GB
GMADR 64 bit BARs
GTTMMADR 64 bit BARs MBASE/MLIMIT
PXPEPBAR 39 bit BAR
DMIBAR 39 bit BAR
MCHBAR 39 bit BAR
TMBAR 64 bit BAR
PMBASE/PMLIMIT 64 bit BAR (using Upper PMBASE/PMLIMIT)
CHAPADR 64 bit BAR
GFXVTBAR 39 bit BARs
VTDPVC0BAR 39 bit BARs
Implementation Notes
• Remap applies to transactions from all interfaces. All upstream PEG/DMI
transactions that are snooped get remapped.
• Upstream PEG/DMI transactions that are not snooped (“Snoop not required”
attribute set) get remapped.
• Upstream reads and writes above TOUUD are treated as invalid cycles.
• Remapped addresses remap starting at TOLUD. They do not remap starting at
TSEG_BASE. DMI and PEG need to be careful with this for both snoop and non-
snoop accesses. In other words, for upstream accesses, the range between
(TOLUD – GfxStolensize – GFXGTTstolensize – TSEGSIZE-DPR) to TOLUD) will
never map directly to memory.
Note: Accesses from PEG/DMI should be decoded as to the type of access before they are
remapped. For instance, a DMI write to FEEx_xxxxh is an interrupt transaction, but
there is a DMI address that will be re-mapped to the DRAM address of FEEx_xxxxh. In
all cases, the remapping of the address is done only after all other decodes have taken
place.
Unmapped addresses between TOLUD and 4 GB
Accesses that don’t hit DRAM or PCI space are subtractive decoded to DMI. Because the
TOLUD register is used to mark the upper limit of DRAM space below the 4 GB
boundary, no address between TOLUD and 4 GB ever decodes directly to main memory.
Thus, even if remap is disabled, any address in this range has a non-memory
destination.
The top of DRAM address space is either:
• TOLUD if there is less than 4 GB of DRAM or 32-bit addressing or
• TOUUD if there is more than 4 GB of DRAM and 36-bit addressing
Note: The system address space includes the remapped range. For instance, if there is 8 GB
of DRAM and 1 GB of PCI space, the system has a 9 GB address space, where DRAM
lies from 0–3 GB and 4–9 GB. BIOS will report an address space of 9 GB to the
operating system.