AXI

Hi Venketesh,

Below factors controls the burst:
Burst_length: AxLEN[7:0]
Burst_size : AxSIZE[3:0]
Burst_type : AxBURST[1:0]

While length can be 1 to 256 for an INCR, size could be 1 to 16, the max burst can be 256*16 giving a size of 4KB.
I hope this helps.

Regards,
Nishant

Hello Muthuvenkatesh,

The 4KB boundary size is essentially a trade-off between supporting a large enough minimum slave size (which could be covered entirely with a single burst and also simplifies address decoders) and wasting too much space for slaves that do not require large address ranges.

Also, although the AXI protocol is independent from the ARM processor architecture, the 4KB boundary size conveniently matches the smallest granule size supported in the ARM VMSA (v7LPAEs, v8 onwards). This guarantees that bursts will never cross the boundary that is described by the smallest virtual to physical address translation page table.

Hope this helps.

Kind regards,
Simone