[idd] transport: configure active instances

idd/LGIdd/LGIdd.vcxproj

@@ -64,6 +64,7 @@
     <ClCompile Include="transport\CFrameHub.cpp" />
     <ClCompile Include="transport\CInputHub.cpp" />
     <ClCompile Include="transport\CTransportManager.cpp" />
+    <ClCompile Include="transport\TransportConfig.cpp" />
     <ClCompile Include="transport\TransportFactory.cpp" />
     <ClCompile Include="transport\lgmp\CIVSHMEM.cpp" />
     <ClCompile Include="transport\lgmp\CRecovery.cpp" />
@@ -123,6 +124,7 @@
     <ClInclude Include="transport\IInputTransport.h" />
     <ClInclude Include="transport\IInputSource.h" />
     <ClInclude Include="transport\ITransport.h" />
+    <ClInclude Include="transport\TransportConfig.h" />
     <ClInclude Include="transport\PreparedFrameBuffer.h" />
     <ClInclude Include="transport\TransportFactory.h" />
     <ClInclude Include="transport\lgmp\CIVSHMEM.h" />

idd/LGIdd/LGIdd.vcxproj.filters

@@ -193,6 +193,9 @@
     <ClInclude Include="transport\ITransport.h">
       <Filter>Transport</Filter>
     </ClInclude>
+    <ClInclude Include="transport\TransportConfig.h">
+      <Filter>Transport</Filter>
+    </ClInclude>
     <ClInclude Include="transport\PreparedFrameBuffer.h">
       <Filter>Transport</Filter>
     </ClInclude>
@@ -324,6 +327,9 @@
     <ClCompile Include="transport\CTransportManager.cpp">
       <Filter>Transport</Filter>
     </ClCompile>
+    <ClCompile Include="transport\TransportConfig.cpp">
+      <Filter>Transport</Filter>
+    </ClCompile>
     <ClCompile Include="transport\TransportFactory.cpp">
       <Filter>Transport</Filter>
     </ClCompile>

idd/LGIdd/config/CSettings.cpp

@@ -80,6 +80,21 @@ CSettings::DisplayModes CSettings::LoadModes()
   return displayModes;
 }
 
+TransportInstances CSettings::LoadTransportInstances() const
+{
+  std::vector<std::wstring> entries;
+  if (!ReadMultiStringValue(L"TransportInstances", entries))
+    return DefaultTransportInstances();
+
+  TransportInstances instances;
+  if (!ParseTransportInstances(entries, instances))
+  {
+    DEBUG_WARN("Invalid transport instance configuration; using defaults");
+    return DefaultTransportInstances();
+  }
+  return instances;
+}
+
 bool CSettings::SetExtraMode(const DisplayMode& mode)
 {
   WCHAR buf[64];
@@ -272,7 +287,8 @@ unsigned CSettings::GetDefaultRefreshMilliHz() const
   return refreshMilliHz ? refreshMilliHz : 60000;
 }
 
-bool CSettings::ReadModesValue(std::vector<std::wstring> &out) const
+bool CSettings::ReadMultiStringValue(const wchar_t * name,
+  std::vector<std::wstring>& out) const
 {
   HKEY hKey = nullptr;
   LONG st   = RegOpenKeyExW(HKEY_LOCAL_MACHINE, LGIDD_REGKEY, 0, KEY_QUERY_VALUE, &hKey);
@@ -280,29 +296,44 @@ bool CSettings::ReadModesValue(std::vector<std::wstring> &out) const
     return false;
 
   DWORD type = 0, cb = 0;
-  st = RegGetValueW(hKey, nullptr, L"Modes", RRF_RT_REG_MULTI_SZ, &type, nullptr, &cb);
+  st = RegGetValueW(hKey, nullptr, name, RRF_RT_REG_MULTI_SZ,
+    &type, nullptr, &cb);
   if (st != ERROR_SUCCESS || cb == 0)  
   {
     RegCloseKey(hKey);
     return false;
   }
 
-  std::vector<wchar_t> buf(cb / sizeof(wchar_t));
-  st = RegGetValueW(hKey, nullptr, L"Modes", RRF_RT_REG_MULTI_SZ, &type, buf.data(), &cb);
+  const DWORD capacity = cb;
+  std::vector<wchar_t> buf(
+    capacity / sizeof(wchar_t) + 2, L'\0');
+  st = RegGetValueW(hKey, nullptr, name, RRF_RT_REG_MULTI_SZ,
+    &type, buf.data(), &cb);
   RegCloseKey(hKey);
-  if (st != ERROR_SUCCESS)
+  if (st != ERROR_SUCCESS || cb > capacity || cb % sizeof(wchar_t))
     return false;
 
-  const wchar_t* p = buf.data();
-  while (*p)
+  const size_t length = cb / sizeof(wchar_t);
+  size_t begin = 0;
+  while (begin < length && buf[begin])
   {
-    out.emplace_back(p);
-    p += (wcslen(p) + 1);
+    size_t end = begin;
+    while (end < length && buf[end])
+      ++end;
+    if (end == length)
+      return false;
+    out.emplace_back(buf.data() + begin, end - begin);
+    begin = end + 1;
   }
 
   return !out.empty();
 }
 
+bool CSettings::ReadModesValue(std::vector<std::wstring> &out) const
+{
+  return ReadMultiStringValue(L"Modes", out);
+}
+
 static std::wstring trim(const std::wstring &s)
 {
   size_t b = 0, e = s.size();

idd/LGIdd/config/CSettings.h

@@ -19,6 +19,8 @@
  */
 
 #pragma once
+#include "transport/TransportConfig.h"
+
 #include <windows.h>
 #include <vector>
 #include <string>
@@ -39,6 +41,7 @@ class CSettings
     CSettings();
 
     DisplayModes LoadModes();
+    TransportInstances LoadTransportInstances() const;
     bool SetExtraMode(const DisplayMode & mode);
     bool GetExtraMode(DisplayMode & mode);
     unsigned GetDefaultRefreshMilliHz() const;
@@ -47,6 +50,8 @@ class CSettings
     bool ReadBoolValue(const wchar_t* name, bool defaultValue = false);
 
   private:
+    bool ReadMultiStringValue(const wchar_t * name,
+      std::vector<std::wstring>& out) const;
     bool ReadModesValue(std::vector<std::wstring> &out) const;
     bool ParseModeString(const std::wstring& in, DisplayMode& out);
 };

idd/LGIdd/transport/CTransportManager.cpp

@@ -238,29 +238,34 @@ void CTransportManager::EndCall(Entry& entry,
   }
 }
 
-bool CTransportManager::Add(BackendId id, const char * name, bool required,
-  bool primary, CreateFn create)
+bool CTransportManager::Add(TransportInstance config, bool primary,
+  CreateFn create)
 {
   CSRWExclusiveLock managerLock(m_lock);
   if (!m_phaseIdle || !m_stoppedEvent || m_phase != Phase::IDLE ||
       m_started || m_stopping ||
-      m_stopped || !id || !name || !create ||
+      m_stopped || !config.enabled || !config.id || config.kind.empty() ||
+      (config.services & ~TRANSPORT_SERVICE_ALL) || !create ||
       m_entryCount == FRAME_MAX_SINKS || (primary && m_primary))
     return false;
 
+  if (primary && (!config.required ||
+      !(config.services & TRANSPORT_SERVICE_FRAME)))
+    return false;
+
   for (unsigned i = 0; i < m_entryCount; ++i)
-    if (m_entries[i]->id == id)
+    if (m_entries[i]->id == config.id)
       return false;
 
   std::unique_ptr<Entry> entry(new (std::nothrow) Entry);
   if (!entry || !entry->idleEvent)
     return false;
 
-  entry->id       = id;
-  entry->name     = name;
-  entry->required = required;
+  entry->id       = config.id;
+  entry->required = config.required;
   entry->primary  = primary;
   entry->create   = create;
+  entry->config   = std::move(config);
 
   Entry * raw = entry.get();
   m_entries[m_entryCount++] = std::move(entry);
@@ -273,15 +278,17 @@ ITransport::OpenResult CTransportManager::OpenEntry(Entry& entry)
 {
   std::shared_ptr<ITransport> transport;
   CreateFn create = nullptr;
+  TransportInstance config;
   {
     CSRWSharedLock entryLock(entry.lock);
     transport = entry.transport;
     create    = entry.create;
+    config    = entry.config;
   }
 
   if (!transport)
   {
-    std::unique_ptr<ITransport> created = create();
+    std::unique_ptr<ITransport> created = create(config);
     transport.reset(created.release());
     CSRWExclusiveLock entryLock(entry.lock);
     entry.transport = transport;
@@ -353,6 +360,8 @@ bool CTransportManager::AddServices(Entry& entry)
   BackendId id = 0;
   uint32_t epoch = 0;
   bool primary = false;
+  bool required = false;
+  uint32_t services = 0;
   bool controlAdded = false;
   bool controlFailed = false;
   bool controlAbsent = false;
@@ -368,6 +377,8 @@ bool CTransportManager::AddServices(Entry& entry)
     id           = entry.id;
     epoch        = entry.epoch;
     primary      = entry.primary;
+    required     = entry.required;
+    services     = entry.config.services;
     controlAdded = entry.controlAdded;
     controlFailed = entry.controlFailed;
     controlAbsent = entry.controlAbsent;
@@ -380,14 +391,16 @@ bool CTransportManager::AddServices(Entry& entry)
   }
 
   if (!transport)
-    return !primary;
+    return !required;
 
   const uint64_t now = GetTickCount64();
   const bool attach = now >= retryAt;
   bool controlRetry = false;
   bool frameRetry   = false;
   bool inputRetry   = false;
-  if (attach && !controlAdded && !controlFailed && !controlAbsent)
+  if (!(services & TRANSPORT_SERVICE_CONTROL))
+    controlAbsent = true;
+  else if (attach && !controlAdded && !controlFailed && !controlAbsent)
   {
     IControlSink * control = transport->Control();
     if (control && m_control.Add(id, epoch, *control))
@@ -406,7 +419,9 @@ bool CTransportManager::AddServices(Entry& entry)
     }
   }
 
-  if (attach && !frameAdded && !frameAbsent)
+  if (!(services & TRANSPORT_SERVICE_FRAME))
+    frameAbsent = true;
+  else if (attach && !frameAdded && !frameAbsent)
   {
     IFrameSink * frame = transport->FrameSink();
     if (frame && m_frames.Bind(id, epoch, primary, *frame))
@@ -425,7 +440,9 @@ bool CTransportManager::AddServices(Entry& entry)
     }
   }
 
-  if (attach && !inputAdded && !inputFailed && !inputAbsent)
+  if (!(services & TRANSPORT_SERVICE_INPUT))
+    inputAbsent = true;
+  else if (attach && !inputAdded && !inputFailed && !inputAbsent)
   {
     IInputSource * input = transport->Input();
     if (input && m_input.Bind(id, epoch, *input))
@@ -450,7 +467,11 @@ bool CTransportManager::AddServices(Entry& entry)
     entry.serviceRetryAt = now + SERVICE_RETRY_DELAY_MS;
   }
 
-  return !primary || frameAdded;
+  const bool servicesReady =
+    (!(services & TRANSPORT_SERVICE_FRAME)   || frameAdded) &&
+    (!(services & TRANSPORT_SERVICE_CONTROL) || controlAdded) &&
+    (!(services & TRANSPORT_SERVICE_INPUT)   || inputAdded);
+  return !required || servicesReady;
 }
 
 void CTransportManager::HandleServiceFailures()
@@ -650,26 +671,25 @@ void CTransportManager::HandleProcessResult(
 
   bool exposed = false;
   bool primary = false;
-  bool required = false;
-  const char * name = nullptr;
+  std::wstring name;
   {
     CSRWSharedLock entryLock(entry.lock);
     exposed  = entry.exposed;
     primary  = entry.primary;
-    required = entry.required;
-    name     = entry.name;
-  }
-
-  if (primary && exposed)
-  {
-    (void)name;
-    DEBUG_WARN("Transport %s requested a restart while its frame interfaces "
-      "are active", name);
-    return;
+    name     = entry.config.kind;
   }
 
   RemoveServices(entry);
-  if (result == ProcessResult::RETRY || !required)
+  if (primary && exposed)
+  {
+    DEBUG_WARN("Transport %ls stopped while its frame interfaces are active",
+      name.c_str());
+    CSRWExclusiveLock entryLock(entry.lock);
+    entry.state = State::FAILED;
+    return;
+  }
+
+  if (result == ProcessResult::RETRY)
   {
     ScheduleRetry(entry);
     return;
@@ -774,6 +794,9 @@ bool CTransportManager::Initialize()
     {
       CSRWSharedLock entryLock(entry.lock);
       transport = entry.transport;
+      if (entry.required && entry.state != State::INITIALIZED &&
+          entry.state != State::READY)
+        success = false;
     }
     EndCall(entry, transport);
   }
@@ -818,7 +841,7 @@ bool CTransportManager::Setup(size_t alignment)
     Entry& entry = *entries[i];
     if (!BeginCall(entry, Call::LIFECYCLE, true))
     {
-      if (entry.primary)
+      if (entry.required)
         success = false;
       continue;
     }
@@ -831,14 +854,18 @@ bool CTransportManager::Setup(size_t alignment)
       transport = entry.transport;
     }
 
-    if ((state == State::INITIALIZED || state == State::READY) &&
-        !SetupEntry(entry, alignment))
+    if (state != State::INITIALIZED && state != State::READY)
+    {
+      if (entry.required)
+        success = false;
+    }
+    else if (!SetupEntry(entry, alignment))
     {
       {
         CSRWSharedLock entryLock(entry.lock);
         state = entry.state;
       }
-      if (entry.primary)
+      if (entry.required)
         success = false;
       else if (state == State::FAILED)
         ScheduleRetry(entry);

idd/LGIdd/transport/CTransportManager.h

@@ -25,13 +25,18 @@
 #include "transport/CFrameHub.h"
 #include "transport/CInputHub.h"
 #include "transport/ITransport.h"
+#include "transport/TransportConfig.h"
 
 #include <memory>
 
+static_assert(TRANSPORT_MAX_INSTANCES == FRAME_MAX_SINKS,
+  "The transport and frame limits must match");
+
 class CTransportManager final
 {
 public:
-  using CreateFn = std::unique_ptr<ITransport> (*)();
+  using CreateFn = std::unique_ptr<ITransport> (*)(
+    const TransportInstance& config);
   using OpenResult = ITransport::OpenResult;
   using ProcessResult = ITransport::ProcessResult;
   using Recovery = ITransport::Recovery;
@@ -90,7 +95,7 @@ private:
     DWORD                       callOwner     = 0;
     bool                        stopRequested = false;
     BackendId                   id       = 0;
-    const char                * name     = nullptr;
+    TransportInstance           config;
     bool                        required = false;
     bool                        primary  = false;
     CreateFn                    create   = nullptr;
@@ -166,8 +171,7 @@ public:
   CTransportManager(const CTransportManager&) = delete;
   CTransportManager& operator=(const CTransportManager&) = delete;
 
-  bool Add(BackendId id, const char * name, bool required, bool primary,
-    CreateFn create);
+  bool Add(TransportInstance config, bool primary, CreateFn create);
 
   OpenResult Open();
   bool Initialize();

idd/LGIdd/transport/ITransport.h

@@ -22,6 +22,7 @@
 
 #include "transport/DirectFrameBufferMemory.h"
 #include "transport/FrameMemoryLimits.h"
+#include "transport/TransportConfig.h"
 
 #include <stddef.h>
 #include <stdint.h>
@@ -30,8 +31,6 @@ class IControlSink;
 class IFrameSink;
 class IInputSource;
 
-using BackendId = uint32_t;
-
 struct SourceKey
 {
   BackendId backend    = 0;

idd/LGIdd/transport/TransportConfig.cpp

@@ -0,0 +1,373 @@
+/**
+ * Looking Glass
+ * Copyright © 2017-2026 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "transport/TransportConfig.h"
+
+#include <errno.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <wctype.h>
+
+namespace
+{
+  enum Field : unsigned
+  {
+    FIELD_ID       = 1U << 0,
+    FIELD_KIND     = 1U << 1,
+    FIELD_ENABLED  = 1U << 2,
+    FIELD_REQUIRED = 1U << 3,
+    FIELD_SERVICES = 1U << 4,
+    FIELD_PRIORITY = 1U << 5,
+    FIELD_SETTINGS = 1U << 6,
+  };
+
+  std::wstring Trim(const std::wstring& value)
+  {
+    size_t begin = 0;
+    size_t end   = value.size();
+    while (begin < end && iswspace(value[begin]))
+      ++begin;
+    while (end > begin && iswspace(value[end - 1]))
+      --end;
+    return value.substr(begin, end - begin);
+  }
+
+  bool Equal(const std::wstring& left, const wchar_t * right)
+  {
+    if (!right)
+      return false;
+
+    size_t index = 0;
+    for (; index < left.size() && right[index]; ++index)
+      if (towlower(left[index]) != towlower(right[index]))
+        return false;
+    return index == left.size() && !right[index];
+  }
+
+  bool ParseBool(const std::wstring& value, bool& result)
+  {
+    if (Equal(value, L"true") || value == L"1")
+    {
+      result = true;
+      return true;
+    }
+    if (Equal(value, L"false") || value == L"0")
+    {
+      result = false;
+      return true;
+    }
+    return false;
+  }
+
+  bool ParseId(const std::wstring& value, BackendId& result)
+  {
+    if (value.empty() || value[0] == L'-')
+      return false;
+
+    wchar_t * end = nullptr;
+    errno = 0;
+    const unsigned long long parsed = wcstoull(value.c_str(), &end, 10);
+    if (errno == ERANGE || !end || *end || !parsed || parsed > UINT32_MAX)
+      return false;
+    result = static_cast<BackendId>(parsed);
+    return true;
+  }
+
+  bool ParsePriority(const std::wstring& value, int32_t& result)
+  {
+    if (value.empty())
+      return false;
+
+    wchar_t * end = nullptr;
+    errno = 0;
+    const long long parsed = wcstoll(value.c_str(), &end, 10);
+    if (errno == ERANGE || !end || *end || parsed < INT32_MIN ||
+        parsed > INT32_MAX)
+      return false;
+    result = static_cast<int32_t>(parsed);
+    return true;
+  }
+
+  bool ParseKind(const std::wstring& value, std::wstring& result)
+  {
+    if (value.empty() || value.size() > 32)
+      return false;
+    for (wchar_t character : value)
+      if (!iswalnum(character) && character != L'_' && character != L'-')
+        return false;
+    result = value;
+    return true;
+  }
+
+  bool AddService(const std::wstring& name, uint32_t& services)
+  {
+    uint32_t service = 0;
+    if (Equal(name, L"frame"))
+      service = TRANSPORT_SERVICE_FRAME;
+    else if (Equal(name, L"control"))
+      service = TRANSPORT_SERVICE_CONTROL;
+    else if (Equal(name, L"input"))
+      service = TRANSPORT_SERVICE_INPUT;
+    else
+      return false;
+
+    if (services & service)
+      return false;
+    services |= service;
+    return true;
+  }
+
+  bool ParseServices(const std::wstring& value, uint32_t& services)
+  {
+    if (Equal(value, L"all"))
+    {
+      services = TRANSPORT_SERVICE_ALL;
+      return true;
+    }
+    if (Equal(value, L"none"))
+    {
+      services = 0;
+      return true;
+    }
+
+    services = 0;
+    size_t begin = 0;
+    while (begin < value.size())
+    {
+      const size_t separator = value.find(L',', begin);
+      const size_t end = separator == std::wstring::npos ?
+        value.size() : separator;
+      if (!AddService(Trim(value.substr(begin, end - begin)), services))
+        return false;
+      if (separator == std::wstring::npos)
+        return true;
+      begin = separator + 1;
+    }
+    return false;
+  }
+
+  bool SetField(const std::wstring& key, const std::wstring& value,
+    TransportInstance& instance, unsigned& fields)
+  {
+    unsigned field = 0;
+    bool valid = false;
+    if (Equal(key, L"id"))
+    {
+      field = FIELD_ID;
+      valid = ParseId(Trim(value), instance.id);
+    }
+    else if (Equal(key, L"kind"))
+    {
+      field = FIELD_KIND;
+      valid = ParseKind(Trim(value), instance.kind);
+    }
+    else if (Equal(key, L"enabled"))
+    {
+      field = FIELD_ENABLED;
+      valid = ParseBool(Trim(value), instance.enabled);
+    }
+    else if (Equal(key, L"required"))
+    {
+      field = FIELD_REQUIRED;
+      valid = ParseBool(Trim(value), instance.required);
+    }
+    else if (Equal(key, L"services"))
+    {
+      field = FIELD_SERVICES;
+      valid = ParseServices(Trim(value), instance.services);
+    }
+    else if (Equal(key, L"priority"))
+    {
+      field = FIELD_PRIORITY;
+      valid = ParsePriority(Trim(value), instance.priority);
+    }
+
+    if (!field || (fields & field) || !valid)
+      return false;
+    fields |= field;
+    return true;
+  }
+
+  bool ParseInstance(const std::wstring& source,
+    TransportInstance& instance)
+  {
+    const std::wstring& line = source;
+    if (Trim(line).empty() || line.size() > 4096)
+      return false;
+
+    unsigned fields = 0;
+    size_t begin = 0;
+    while (begin < line.size())
+    {
+      const size_t separator = line.find(L';', begin);
+      const size_t end = separator == std::wstring::npos ?
+        line.size() : separator;
+      const std::wstring field = line.substr(begin, end - begin);
+      const size_t equals = field.find(L'=');
+      if (equals == std::wstring::npos)
+        return false;
+
+      const std::wstring key = Trim(field.substr(0, equals));
+      if (Equal(key, L"settings"))
+      {
+        if (fields & FIELD_SETTINGS)
+          return false;
+        instance.settings = line.substr(begin + equals + 1);
+        fields |= FIELD_SETTINGS;
+        begin = line.size();
+        break;
+      }
+
+      if (!SetField(key, field.substr(equals + 1), instance, fields))
+        return false;
+      if (separator == std::wstring::npos)
+        break;
+      begin = separator + 1;
+      if (begin == line.size())
+        return false;
+    }
+
+    return (fields & (FIELD_ID | FIELD_KIND)) ==
+      (FIELD_ID | FIELD_KIND);
+  }
+
+  int FindKind(const std::wstring& name,
+    const TransportKind * kinds, unsigned kindCount)
+  {
+    for (unsigned i = 0; i < kindCount; ++i)
+      if (kinds[i].name && Equal(name, kinds[i].name))
+        return static_cast<int>(i);
+    return -1;
+  }
+
+  bool TryResolve(const TransportInstances& instances,
+    const TransportKind * kinds, unsigned kindCount,
+    ResolvedTransportInstances& resolved)
+  {
+    if (!kinds || !kindCount || instances.empty() ||
+        instances.size() > TRANSPORT_MAX_INSTANCES)
+      return false;
+
+    ResolvedTransportInstances result;
+    int primary = -1;
+    for (const TransportInstance& instance : instances)
+    {
+      if (!instance.id || instance.kind.empty() ||
+          (instance.services & ~TRANSPORT_SERVICE_ALL))
+        return false;
+
+      for (const TransportInstance& other : instances)
+        if (&other != &instance && other.id == instance.id)
+          return false;
+
+      const int kindIndex = FindKind(instance.kind, kinds, kindCount);
+      if (kindIndex < 0 || !kinds[kindIndex].activeLimit)
+        return false;
+      if (!instance.enabled)
+        continue;
+
+      unsigned active = 0;
+      for (const ResolvedTransportInstance& existing : result)
+        if (existing.kindIndex == static_cast<unsigned>(kindIndex))
+          ++active;
+      if (active == kinds[kindIndex].activeLimit ||
+          result.size() == TRANSPORT_MAX_INSTANCES)
+        return false;
+
+      ResolvedTransportInstance selected;
+      selected.config    = instance;
+      selected.kindIndex = static_cast<unsigned>(kindIndex);
+      if (instance.required &&
+          (instance.services & TRANSPORT_SERVICE_FRAME) &&
+          (primary < 0 || instance.priority >
+            result[primary].config.priority))
+        primary = static_cast<int>(result.size());
+      result.push_back(selected);
+    }
+
+    if (primary < 0)
+      return false;
+    result[primary].primary = true;
+    resolved.swap(result);
+    return true;
+  }
+}
+
+TransportInstances DefaultTransportInstances()
+{
+  TransportInstance instance;
+  instance.id       = 1;
+  instance.kind     = L"LGMP";
+  instance.enabled  = true;
+  instance.required = true;
+  instance.services = TRANSPORT_SERVICE_ALL;
+  instance.priority = 0;
+
+  TransportInstances instances;
+  instances.push_back(instance);
+  return instances;
+}
+
+bool ParseTransportInstances(const std::vector<std::wstring>& entries,
+  TransportInstances& instances)
+{
+  TransportInstances parsed;
+  if (entries.empty() || entries.size() > TRANSPORT_MAX_INSTANCES)
+    return false;
+
+  bool hasRequiredFrame = false;
+  for (const std::wstring& entry : entries)
+  {
+    TransportInstance instance;
+    if (!ParseInstance(entry, instance))
+      return false;
+
+    for (const TransportInstance& existing : parsed)
+      if (existing.id == instance.id)
+        return false;
+
+    if (instance.enabled && instance.required &&
+        (instance.services & TRANSPORT_SERVICE_FRAME))
+      hasRequiredFrame = true;
+    parsed.push_back(instance);
+  }
+
+  if (!hasRequiredFrame)
+    return false;
+  instances.swap(parsed);
+  return true;
+}
+
+bool ResolveTransportInstances(const TransportInstances& configured,
+  const TransportKind * kinds, unsigned kindCount,
+  ResolvedTransportInstances& resolved, bool& usedDefaults)
+{
+  usedDefaults = false;
+  if (TryResolve(configured, kinds, kindCount, resolved))
+    return true;
+
+  usedDefaults = true;
+  const TransportInstances defaults = DefaultTransportInstances();
+  if (TryResolve(defaults, kinds, kindCount, resolved))
+    return true;
+
+  resolved.clear();
+  return false;
+}

idd/LGIdd/transport/TransportConfig.h

@@ -0,0 +1,74 @@
+/**
+ * Looking Glass
+ * Copyright © 2017-2026 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <string>
+#include <vector>
+
+using BackendId = uint32_t;
+
+enum TransportService : uint32_t
+{
+  TRANSPORT_SERVICE_FRAME   = 1U << 0,
+  TRANSPORT_SERVICE_CONTROL = 1U << 1,
+  TRANSPORT_SERVICE_INPUT   = 1U << 2,
+  TRANSPORT_SERVICE_ALL     = TRANSPORT_SERVICE_FRAME |
+    TRANSPORT_SERVICE_CONTROL | TRANSPORT_SERVICE_INPUT,
+};
+
+struct TransportInstance
+{
+  BackendId   id       = 0;
+  std::wstring kind;
+  bool         enabled  = true;
+  bool         required = false;
+  uint32_t     services = TRANSPORT_SERVICE_ALL;
+  int32_t      priority = 0;
+  std::wstring settings;
+};
+
+using TransportInstances = std::vector<TransportInstance>;
+
+static const unsigned TRANSPORT_MAX_INSTANCES = 8;
+
+struct TransportKind
+{
+  const wchar_t * name;
+  unsigned        activeLimit;
+};
+
+struct ResolvedTransportInstance
+{
+  TransportInstance config;
+  unsigned          kindIndex = 0;
+  bool              primary   = false;
+};
+
+using ResolvedTransportInstances =
+  std::vector<ResolvedTransportInstance>;
+
+TransportInstances DefaultTransportInstances();
+bool ParseTransportInstances(const std::vector<std::wstring>& entries,
+  TransportInstances& instances);
+bool ResolveTransportInstances(const TransportInstances& configured,
+  const TransportKind * kinds, unsigned kindCount,
+  ResolvedTransportInstances& resolved, bool& usedDefaults);

idd/LGIdd/transport/TransportFactory.cpp

@@ -20,21 +20,66 @@
 
 #include "transport/TransportFactory.h"
 
+#include "CDebug.h"
+#include "config/CSettings.h"
 #include "transport/CTransportManager.h"
 #include "transport/lgmp/CLGMPTransport.h"
 
 #include <new>
 
-static std::unique_ptr<ITransport> CreateLGMP()
+namespace
 {
-  return std::unique_ptr<ITransport>(new (std::nothrow) CLGMPTransport());
+  struct Provider
+  {
+    CTransportManager::CreateFn create;
+  };
+
+  std::unique_ptr<ITransport> CreateLGMP(
+    const TransportInstance& config)
+  {
+    return std::unique_ptr<ITransport>(
+      new (std::nothrow) CLGMPTransport(config));
+  }
+
+  const TransportKind KINDS[] =
+  {
+    { L"LGMP", 1 },
+  };
+
+  const Provider PROVIDERS[] =
+  {
+    { CreateLGMP },
+  };
+
+  static_assert(ARRAYSIZE(KINDS) == ARRAYSIZE(PROVIDERS),
+    "Every transport kind must have a provider");
+
+  std::unique_ptr<CTransportManager> Build(
+    const ResolvedTransportInstances& instances)
+  {
+    std::unique_ptr<CTransportManager> manager(
+      new (std::nothrow) CTransportManager());
+    if (!manager)
+      return std::unique_ptr<CTransportManager>();
+
+    for (const ResolvedTransportInstance& instance : instances)
+      if (!manager->Add(instance.config, instance.primary,
+          PROVIDERS[instance.kindIndex].create))
+        return std::unique_ptr<CTransportManager>();
+    return manager;
+  }
 }
 
 std::unique_ptr<CTransportManager> CreateTransport()
 {
-  std::unique_ptr<CTransportManager> manager(
-    new (std::nothrow) CTransportManager());
-  if (!manager || !manager->Add(1, "LGMP", true, true, CreateLGMP))
+  TransportInstances instances = g_settings.LoadTransportInstances();
+  ResolvedTransportInstances resolved;
+  bool usedDefaults = false;
+  if (!ResolveTransportInstances(instances, KINDS, ARRAYSIZE(KINDS),
+      resolved, usedDefaults))
     return std::unique_ptr<CTransportManager>();
-  return manager;
+  if (usedDefaults)
+    DEBUG_WARN("Unsupported transport instance configuration; using defaults");
+
+  return Build(resolved);
 }

idd/LGIdd/transport/lgmp/CLGMPTransport.cpp

@@ -48,7 +48,8 @@ static bool TranslateFrameScheduleFlags(
   return true;
 }
 
-CLGMPTransport::CLGMPTransport() :
+CLGMPTransport::CLGMPTransport(const TransportInstance& config) :
+  m_config(config),
   m_control(m_host),
   m_frames(m_host, m_ivshmem),
   m_input(m_host)

idd/LGIdd/transport/lgmp/CLGMPTransport.h

@@ -33,6 +33,7 @@
 class CLGMPTransport final : public ITransport
 {
 private:
+  TransportInstance    m_config;
   // Keep this declaration order. Destruction must release frame and control
   // allocations before the LGMP host and its IVSHMEM mapping are destroyed.
   CIVSHMEM            m_ivshmem;
@@ -44,7 +45,7 @@ private:
   std::atomic<bool>   m_ready = false;
 
 public:
-  CLGMPTransport();
+  explicit CLGMPTransport(const TransportInstance& config);
   ~CLGMPTransport() override = default;
 
   CLGMPTransport(const CLGMPTransport&) = delete;