From 80c3bd3bdff45b508375d4e297c68a452a905c6f Mon Sep 17 00:00:00 2001
From: Yu-hsin Wang <yuhsingw@google.com>
Date: Fri, 21 Oct 2022 11:53:12 +0800
Subject: [PATCH] mem: introduce bad command error to packet commands

The bad command is used to model a request is sent to target but the
target cannot make it. The bad command error is designed to model AXI
SLVERR.

Change-Id: I8142df36a5ed3e461493796266821a2b30a3415e
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/64872
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Earl Ou <shunhsingou@google.com>
---
 src/mem/packet.cc |  4 ++++
 src/mem/packet.hh | 15 +++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/src/mem/packet.cc b/src/mem/packet.cc
index 3cd1bb9a29..31dc330cab 100644
--- a/src/mem/packet.cc
+++ b/src/mem/packet.cc
@@ -214,6 +214,10 @@ MemCmd::commandInfo[] =
     { {IsResponse, IsError}, InvalidCmd, "InvalidDestError" },
     /* BadAddressError   -- memory address invalid */
     { {IsResponse, IsError}, InvalidCmd, "BadAddressError" },
+    /* ReadError -- packet dest unable to fulfill read command */
+    { {IsRead, IsResponse, IsError}, InvalidCmd, "ReadError" },
+    /* WriteError -- packet dest unable to fulfill write command */
+    { {IsWrite, IsResponse, IsError}, InvalidCmd, "WriteError" },
     /* FunctionalReadError */
     { {IsRead, IsResponse, IsError}, InvalidCmd, "FunctionalReadError" },
     /* FunctionalWriteError */
diff --git a/src/mem/packet.hh b/src/mem/packet.hh
index 7d3263412c..9238dbec00 100644
--- a/src/mem/packet.hh
+++ b/src/mem/packet.hh
@@ -133,6 +133,8 @@ class MemCmd
         // compatibility
         InvalidDestError,  // packet dest field invalid
         BadAddressError,   // memory address invalid
+        ReadError,         // packet dest unable to fulfill read command
+        WriteError,        // packet dest unable to fulfill write command
         FunctionalReadError, // unable to fulfill functional read
         FunctionalWriteError, // unable to fulfill functional write
         // Fake simulator-only commands
@@ -785,6 +787,19 @@ class Packet : public Printable
         cmd = MemCmd::BadAddressError;
     }
 
+    // Command error conditions. The request is sent to target but the target
+    // cannot make it.
+    void
+    setBadCommand()
+    {
+        assert(isResponse());
+        if (isWrite()) {
+            cmd = MemCmd::WriteError;
+        } else {
+            cmd = MemCmd::ReadError;
+        }
+    }
+
     void copyError(Packet *pkt) { assert(pkt->isError()); cmd = pkt->cmd; }
 
     Addr getAddr() const { assert(flags.isSet(VALID_ADDR)); return addr; }