[m5-dev] 3 Bugs in the checkpoint_restore for spec2006

[Richard Strong]

Hi all,

I uncovered 3 bugs when trying to resume in ALPHA_SE from a checkpoint for
the spec2006 benchmarks. They are:

(1) Unserializing curTick failed because the checkpoint file wrote
curTick()=, but the unserializing code was expecting curTick=

(2) The mode bit was not being stored in the file descriptor checkpoint. I
added a feature to store the mode bit.

(3) The dup function was duplicating the wrong file descriptor.

Let me know what you think, I give the diff below along with a traceflag
that allowed me to find the problem.

Best,
-Rick

diff --git a/src/sim/SConscript b/src/sim/SConscript
--- a/src/sim/SConscript
+++ b/src/sim/SConscript
@@ -77,3 +77,4 @@
 TraceFlag('Thread')
 TraceFlag('Timer')
 TraceFlag('VtoPhys')
+TraceFlag('FileDescriptors')
diff --git a/src/sim/process.cc b/src/sim/process.cc
--- a/src/sim/process.cc
+++ b/src/sim/process.cc
@@ -268,6 +268,7 @@
 int
 Process::alloc_fd(int sim_fd, string filename, int flags, int mode, bool
pipe)
 {
+    DPRINTF(FileDescriptors, "alloc_fd fd:%d filename:%s\n", sim_fd,
filename);
     // in case open() returns an error, don't allocate a new fd
     if (sim_fd == -1)
         return -1;
@@ -295,6 +296,7 @@
 void
 Process::free_fd(int tgt_fd)
 {
+    DPRINTF(FileDescriptors, "free_fd fd:%d name:%s\n", tgt_fd, "NULL");
     Process::FdMap *fdo = &fd_map[tgt_fd];
     if (fdo->fd == -1)
         warn("Process::free_fd: request to free unused fd %d", tgt_fd);
@@ -324,8 +326,16 @@
 {
     if (tgt_fd > MAX_FD)
         panic("sim_fd_obj called in fd out of range.");
+

-    return &fd_map[tgt_fd];
+    //return &fd_map[tgt_fd];
+    for (int x = 0; x <= MAX_FD; x++) {
+           if (fd_map[x].fd == tgt_fd){
+               return &fd_map[x];
+           }
+     }
+     panic("sim_fd_obj could not find system fd.");
+     return NULL;
 }

 bool
@@ -458,6 +468,7 @@
         if (fdo->fd != -1) {
             fdo->fileOffset = lseek(fdo->fd, 0, SEEK_CUR);
         } else {
+                DPRINTF(FileDescriptors, "find_file_offsets fd:%d
filename:%s\n", fdo->fd, fdo->filename);
                 fdo->filename = "NULL";
                 fdo->fileOffset = 0;
         }
@@ -480,6 +491,7 @@
     SERIALIZE_SCALAR(flags);
     SERIALIZE_SCALAR(readPipeSource);
     SERIALIZE_SCALAR(fileOffset);
+    SERIALIZE_SCALAR(mode);
 }

 void
@@ -491,6 +503,7 @@
     UNSERIALIZE_SCALAR(flags);
     UNSERIALIZE_SCALAR(readPipeSource);
     UNSERIALIZE_SCALAR(fileOffset);
+    UNSERIALIZE_SCALAR(mode);
 }

 void
diff --git a/src/sim/serialize.cc b/src/sim/serialize.cc
--- a/src/sim/serialize.cc
+++ b/src/sim/serialize.cc
@@ -411,7 +411,7 @@
 {
     const string &section = name();
     Tick tick;
-    paramIn(cp, section, "curTick", tick);
+    paramIn(cp, section, "curTick()", tick);
     curTick(tick);

     mainEventQueue.unserialize(cp, "MainEventQueue");

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