Tile Link example

apaj edited this page Sep 3, 2018 · 1 revision

I try to do some simple works for learning to learn rocket chip.

I leverage SRAM( in rocket-chip/src/main/scala/tilelink/) and attach it on rocket chip system bus. However, it fails to generate out the emulator.

Below code is my RAM configuration(rocket system is 64 bits):

trait HasPRAM extends HasSystemBus { implicit val p: Parameters

private val address = 0x2000

val ram = LazyModule(new TLRAM(AddressSet(0x2000, 0xff), beatBytes = 8 ))

ram.node := sbus.toSlave }

The main error message:

Caused by: java.lang.IllegalArgumentException: requirement failed: MemoryMap region ram only supports TransferSizes[1, 8] Get, but must support TransferSizes[1, 64]

I try to trace out and fix it. And I find the error is related to TLBPageLookup. However, I still cannot fix with some trying. Can anyone helps me to point out whats wrong about it?

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You can use TLFragmenter which is there in tilelink/Fragmenter.scala

ram.node := TLFragmenter(8, 64) := sbus.toSlave

TLFragmenter will fragment the data transaction size into range that is supported by manager and generate appropriate data request/response

8 since there is no need to fragment accesses with size lesser than beatBytes 64 since that is the maximum possible transfer size as shown by your error

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