1diff --git a/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp b/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp
2index e3707365a9c3..c4a9c82f3c63 100644
3--- a/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp
4+++ b/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp
5@@ -38,6 +38,8 @@ public:
6
7   size_t DoReadMemory(lldb::addr_t addr, void *buf, size_t size,
8                       lldb_private::Status &error) override;
9+  size_t DoWriteMemory(lldb::addr_t vm_addr, const void *buf,
10+                       size_t size, Status &error) override;
11
12 private:
13   fvc_t *m_fvc;
14@@ -185,6 +187,7 @@ bool ProcessFreeBSDKernel::DoUpdateThreadList(ThreadList &old_thread_list,
15     // iterate through a linked list of all processes
16     // allproc is a pointer to the first list element, p_list field
17     // (found at offset_p_list) specifies the next element
18+    lldb::addr_t prev = 0;
19     for (lldb::addr_t proc =
20              ReadPointerFromMemory(FindSymbol("allproc"), error);
21          proc != 0 && proc != LLDB_INVALID_ADDRESS;
22@@ -195,6 +198,8 @@ bool ProcessFreeBSDKernel::DoUpdateThreadList(ThreadList &old_thread_list,
23       char comm[fbsd_maxcomlen + 1];
24       ReadCStringFromMemory(proc + offset_p_comm, comm, sizeof(comm), error);
25
26+      bool interesting = false;
27+
28       // iterate through a linked list of all process' threads
29       // the initial thread is found in process' p_threads, subsequent
30       // elements are linked via td_plist field
31@@ -231,6 +236,7 @@ bool ProcessFreeBSDKernel::DoUpdateThreadList(ThreadList &old_thread_list,
32           // NB: dumppcb can be LLDB_INVALID_ADDRESS if reading it failed
33           pcb_addr = dumppcb;
34           thread_desc += " (crashed)";
35+          interesting = true;
36         } else if (oncpu != -1) {
37           // if we managed to read stoppcbs and pcb_size, use them to find
38           // the correct PCB
39@@ -239,13 +245,27 @@ bool ProcessFreeBSDKernel::DoUpdateThreadList(ThreadList &old_thread_list,
40           else
41             pcb_addr = LLDB_INVALID_ADDRESS;
42           thread_desc += llvm::formatv(" (on CPU {0})", oncpu);
43+          interesting = true;
44         }
45
46         ThreadSP thread_sp{
47             new ThreadFreeBSDKernel(*this, tid, pcb_addr, thread_desc)};
48         new_thread_list.AddThread(thread_sp);
49       }
50+
51+      if (interesting) {
52+        printf("pid %d is interesting\n", pid);
53+        if (prev != 0) {
54+          printf("will link %d to %d\n", prev, proc);
55+          if (!WritePointerToMemory(prev + offset_p_list, proc, error))
56+            assert(0 && "write failed");
57+        }
58+        prev = proc;
59+      }
60     }
61+    printf("last: %d\n", prev);
62+    if (!WritePointerToMemory(prev + offset_p_list, 0, error))
63+      assert(0 && "write failed");
64   } else {
65     const uint32_t num_threads = old_thread_list.GetSize(false);
66     for (uint32_t i = 0; i < num_threads; ++i)
67@@ -295,6 +315,18 @@ size_t ProcessFreeBSDKernelFVC::DoReadMemory(lldb::addr_t addr, void *buf,
68   return rd;
69 }
70
71+size_t ProcessFreeBSDKernelFVC::DoWriteMemory(lldb::addr_t vm_addr, const void *buf,
72+                       size_t size, Status &error) {
73+  ssize_t rd = 0;
74+  rd = fvc_write(m_fvc, vm_addr, buf, size);
75+  printf("fvc_write(%p, %p, %d) -> %d\n", vm_addr, buf, size, rd);
76+  if (rd < 0 || static_cast<size_t>(rd) != size) {
77+    error = Status::FromErrorStringWithFormat("Writing memory failed: %s", GetError());
78+    return rd > 0 ? rd : 0;
79+  }
80+  return rd;
81+}
82+
83 const char *ProcessFreeBSDKernelFVC::GetError() { return fvc_geterr(m_fvc); }
84
85 #endif // LLDB_ENABLE_FBSDVMCORE
86