Table 4-4: BAR Registers
Parameter
Value
Description
Type
Disabled
64-bit prefetchable memory
32-bit non-prefetchable memory
32-bit prefetchable memory
I/O address space
If you select 64-bit prefetchable memory, 2
contiguous BARs are combined to form a 64-bit
prefetchable BAR; you must set the higher numbered
BAR to Disabled. A non-prefetchable 64
-
bit BAR is
not supported because in a typical system, the Root
Port Type 1 Configuration Space sets the maximum
non
-
prefetchable memory window to 32 bits. The
BARs can also be configured as separate 32
-
bit
memories.
Defining memory as prefetchable allows contiguous
data to be fetched ahead. Prefetching memory is
advantageous when the requestor may require more
data from the same region than was originally
requested. If you specify that a memory is prefetch‐
able, it must have the following 2 attributes:
• Reads do not have side effects such as changing
the value of the data read
• Write merging is allowed
The 32-bit prefetchable memory and I/O address
space BARs are only available for the Legacy
Endpoint.
Size
N/A
Qsys automatically calculates the required size after
you connect your components.
Device Identification Registers
Table 4-5: Device ID Registers
The following table lists the default values of the read
-
only Device ID registers. You can use the parameter editor
to change the values of these registers. Refer to
Type 0 Configuration Space Registers
for the layout of the Device
Identification registers.
Register Name
Range
Default Value
Description
Vendor ID
16 bits
0x00001172
Sets the read-only value of the
Vendor ID
register. This
parameter cannot be set to 0xFFFF, per the
PCI Express
Specification
.
Address offset: 0x000.
4-6
Device Identification Registers
UG-01145_avmm_dma
2015.11.02
Altera Corporation
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