Prior to this PR, the error device was allowed to be cached by
multiple actors despite never probing any of them. This is a
pretty unusual set of properties that has caused us trouble
several times now in the past.
Let's instead put the Error device into one of two very well
established categories: a straight-up MMIO device or a tracked
memory region.
* SourceShrinker: preserve FIFO guarantees of slaves
* tilelink: document that Releases can use TtoT, BtoB, and NtoN
TtoT is needed for write-through caches.
- adds a mutable singleton (PlusArgArtefacts) to store information
about Rocket PlusArgs
- adds methods to PlusArgArtefacts to emit C snippets that are
consumed by emulator.cc for correct argument parsing and help text
generation
- emits snippets in $(CONFIG).plusArgs via BaseCoreplex-set
ElaborationArtefacts
- modify emulator/Makefrag-verilator to include $(CONFIG).plusArgs
- cleanup help text (docstring) for existing PlusArgs
Signed-off-by: Schuyler Eldridge <schuyler.eldridge@gmail.com>
* Make dts generation reusable across tile subclasses
* First attempt to standardize tile IO nodes and connect methods
* hartid => hartId when talking about scala Ints
The reason for the :=? operator was for when you have an adapter chain
whose direction of cardinality you could not know. We used explicit
directives to tell these compositions which way to go.
Unfortunately, that makes the API leaky. You think the chain of adapters
is just one adapter, but you have to use strange Cardinality scopes to
use it. That's just bad.
The new :*=* just automagically figures it out from the graph.
This removes the mostly obsolete 'numIn/Out' range restrictions on nodes.
It also makes it possible to connect optional crossbars that disappear.
val x = TLXbar()
x := master
slave := x
val y = TLXbar()
x :=* y // only connect y if it gets used
This will create crossbar x, but crossbar y will disappear.
This is a follow-up to PR #1108.
Rather than increasing the number of transactions we allow to be inflight,
instead just block TL when early source re-use happens. This is a better
fix since it means we don't pay mostly wasted downstream hardware to handle
an additional transaction inflight that almost never happens.
* TLToAXI4: fix WaR for single-source FIFO masters
* TLToAXI4: fix potential counter overflow => WaR hazard
If you have a FIFO master with 2^n-1 sources that performs early
source re-use, the old code could potentially break FIFO order.
Fragmenter: add a third case for earlyAck (PutFulls only)
It seems quite common to have a device that is backed by ECC. When
performing a multibeat PutPartial, these devices can exhibit their
first error on the last beat (if it had an incomplete write mask
for that beat, which required read-write-modifying corrupted data).
Generally, these devices have ECC granularity <= the bus width. In
those cases, if you send a PutFull, the first beat carries the
error value for the whole burst. Consider:
If the PutFull was below the granularity, it was a single beat.
If the PutFull was multi-beat, it exceeds the granularity.
Therefore, an important variation on the earlyAck optimization is
the case where only PutFulls receive an earlyAck.
* tilelink: ToAXI4 should format it's error message
* WithStatelessBridge: mark the memory bus incoherent and cacheable
... and hope that the user doesn't put more than one master down.
From the AHB spec:
"A slave only has to provide valid data when a transfer completes with an OKAY
response. ERROR responses do not require valid read data."
This makes it possible to treat chained composition associatively.
x := y :=? z :=* a ...
It also makes it easy to chain multiple optional adapters:
node :=? (Seq(a, b) ++ c ++ d)
