Visible to Intel only — GUID: ngc1625848097687
Ixiasoft
Visible to Intel only — GUID: ngc1625848097687
Ixiasoft
7.3.7.1. FPGA-to-HPS CCU to SDRAM/OCRAM memory (Cache Non-Allocate)
If your logic issues a Cache Non-Allocate transaction, the CCU maintains coherency but does not allocate in the cache. This is useful when you want to maintain coherency but not thrash the cache.
Reads
- On cache hits, read data is returned by the cache.
- On cache misses, read data is returned from main memory and not allocated (stored) in cache.
ATTRIBUTE | VALUE | NOTE |
---|---|---|
ARDOMAIN[1:0] | ’b01 | Inner Sharable |
ARBAR[1:0] | ‘b00 | Normal access, respecting barriers |
ARSNOOP[3:0] | ‘b0000 | ReadOnce |
ARCACHE[3:0] | ‘b1011 | Write-back No-allocate |
AxUSER[7:0] | ‘b00000100 | 0x04 = CCU |
AxPROT[2:0] | ‘b011 or ‘b010 | Privileged access. Non-Secure access. Data access (or can be ‘b010 for Unprivileged access) |
AxLEN[7:0] | The burst length for: WRAP burst type must be 1, 2, 4, 8 or 16 transfers. INCR burst type is 1 to 256 transfers. |
|
AxSIZE[2:0] | The number of bytes in a transfer must be equal to the data bus width | |
AxBURST[1:0] | ‘b01 or ‘b10 | Must be INCR(‘b01) or WRAP(‘b10) |
AxLOCK[1:0] | ‘b00 | Must be normal access |
AxQOS | Do not care |
Writes
- On cache hits, write data is stored in cache.
- On cache misses, write data is stored to main memory.
ATTRIBUTE | VALUE | NOTE |
AWDOMAIN[1:0] | ’b01 | Inner Sharable |
AWBAR[1:0] | ‘b00 | Normal access, respecting barriers |
AWSNOOP[2:0] | ‘b000 | WriteUnique (can be ‘b001 for WriteLineUnique) |
AWCACHE[3:0] | ‘b0111 | Write-back No-allocate |
AxUSER[7:0] | ‘b00000100 | 0x04 = CCU |
AxPROT[2:0] | ‘b011 or ‘b010 | Privileged access. Non-Secure access. Data access (or can be ‘b010 for Unprivileged access) |
AxLEN[7:0] | The burst length for: WRAP burst type must be 1, 2, 4, 8 or 16 transfers. INCR burst type is 1 to 256 transfers. |
|
AxSIZE[2:0] | The number of bytes in a transfer must be equal to the data bus width | |
AxBURST[1:0] | ‘b01 or ‘b10 | Must be INCR(‘b01) or WRAP(‘b10) |
AxLOCK[1:0] | ‘b00 | Must be normal access |
AxQOS | Do not care |