[idd] transport: intersect frame capabilities

idd/LGIdd/transport/CTransportManager.cpp

@@ -328,6 +328,8 @@ ITransport::OpenResult CTransportManager::OpenEntry(Entry& entry)
 bool CTransportManager::InitializeEntry(Entry& entry)
 {
   std::shared_ptr<ITransport> transport;
+  uint32_t services = 0;
+  bool required = false;
   {
     CSRWSharedLock entryLock(entry.lock);
     if (entry.state == State::INITIALIZED || entry.state == State::READY)
@@ -335,6 +337,8 @@ bool CTransportManager::InitializeEntry(Entry& entry)
     if (entry.state != State::OPEN)
       return false;
     transport = entry.transport;
+    services  = entry.config.services;
+    required  = entry.required;
   }
 
   if (!transport || !transport->Initialize())
@@ -344,12 +348,30 @@ bool CTransportManager::InitializeEntry(Entry& entry)
     return false;
   }
 
-  const FrameMemoryLimits limits = transport->GetMemoryLimits();
+  std::shared_ptr<const FrameCaps> frameCaps;
+  if (services & TRANSPORT_SERVICE_FRAME)
+  {
+    frameCaps = transport->GetFrameCaps();
+    if (!frameCaps && required)
+    {
+      CSRWExclusiveLock entryLock(entry.lock);
+      entry.state = State::FAILED;
+      return false;
+    }
+  }
+  const bool hasFrameCaps = frameCaps != nullptr;
   {
     CSRWExclusiveLock entryLock(entry.lock);
-    entry.limits      = limits;
-    entry.limitsValid = true;
-    entry.state       = State::INITIALIZED;
+    // The first successfully initialized instance fixes the advertised
+    // capability contract. Recreating an instance must not change the mode
+    // list during a runtime restart.
+    if (!entry.frameCaps)
+      entry.frameCaps = std::move(frameCaps);
+    // A best-effort instance without a capability contract can continue to
+    // provide its other configured services, but must not receive frames.
+    entry.frameAbsent = (services & TRANSPORT_SERVICE_FRAME) &&
+      !hasFrameCaps;
+    entry.state = State::INITIALIZED;
   }
   return true;
 }
@@ -627,8 +649,6 @@ void CTransportManager::RetryEntry(Entry& entry, uint64_t now,
   {
     CSRWExclusiveLock entryLock(entry.lock);
     entry.transport.reset();
-    entry.limits       = FrameMemoryLimits {};
-    entry.limitsValid  = false;
     entry.directMemory = DirectFrameBufferMemory {};
     entry.directMemoryValid = false;
     entry.setupDone    = false;
@@ -1180,20 +1200,42 @@ void CTransportManager::RecoveryStatus(const SourceKey& source,
   }
 }
 
-FrameMemoryLimits CTransportManager::GetMemoryLimits() const
+bool CTransportManager::CanUseMode(const FrameMode& mode,
+  uint32_t * requiredSizeMiB) const
 {
+  if (requiredSizeMiB)
+    *requiredSizeMiB = 0;
+
+  std::shared_ptr<const FrameCaps> caps[FRAME_MAX_SINKS];
+  unsigned capsCount = 0;
+  Entry * entries[FRAME_MAX_SINKS] = {};
+  const unsigned count = Entries(entries);
+  for (unsigned i = 0; i < count; ++i)
   {
-    CSRWSharedLock managerLock(m_lock);
-    if (m_stopping || m_stopped)
-      return FrameMemoryLimits {};
+    Entry& entry = *entries[i];
+    CSRWSharedLock entryLock(entry.lock);
+    if (!entry.required ||
+        !(entry.config.services & TRANSPORT_SERVICE_FRAME))
+      continue;
+    if (!entry.frameCaps)
+      return false;
+    caps[capsCount++] = entry.frameCaps;
   }
 
-  Entry * primary = Primary();
-  if (!primary)
-    return FrameMemoryLimits {};
+  if (!capsCount)
+    return false;
 
-  CSRWSharedLock entryLock(primary->lock);
-  return primary->limitsValid ? primary->limits : FrameMemoryLimits {};
+  bool supported = true;
+  for (unsigned i = 0; i < capsCount; ++i)
+  {
+    uint32_t hint = 0;
+    if (caps[i]->CanUseMode(mode, capsCount == 1 ? &hint : nullptr))
+      continue;
+    supported = false;
+    if (requiredSizeMiB && capsCount == 1)
+      *requiredSizeMiB = hint;
+  }
+  return supported;
 }
 
 DirectFrameBufferMemory CTransportManager::GetDirectMemory() const

idd/LGIdd/transport/CTransportManager.h

@@ -32,7 +32,7 @@
 static_assert(TRANSPORT_MAX_INSTANCES == FRAME_MAX_SINKS,
   "The transport and frame limits must match");
 
-class CTransportManager final
+class CTransportManager final : public FrameCaps
 {
 public:
   using CreateFn = std::unique_ptr<ITransport> (*)(
@@ -117,8 +117,7 @@ private:
     bool                        syncPending  = false;
     bool                        recoveryPending = false;
     RecoveryUpdate              recovery;
-    FrameMemoryLimits           limits;
-    bool                        limitsValid = false;
+    std::shared_ptr<const FrameCaps> frameCaps;
     DirectFrameBufferMemory     directMemory;
     bool                        directMemoryValid = false;
     std::shared_ptr<ITransport> exposedTransport;
@@ -183,7 +182,8 @@ public:
     uint64_t session, uint32_t serial, bool active,
     Recovery state, uint32_t error);
 
-  FrameMemoryLimits GetMemoryLimits() const;
+  bool CanUseMode(const FrameMode& mode,
+    uint32_t * requiredSizeMiB = nullptr) const override;
   DirectFrameBufferMemory GetDirectMemory() const;
 
   IFrameTransport& Frames();

idd/LGIdd/transport/FrameCaps.h

@@ -0,0 +1,41 @@
+/**
+ * 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>
+
+struct FrameMode
+{
+  uint32_t width          = 0;
+  uint32_t height         = 0;
+  uint32_t refreshMilliHz = 0;
+};
+
+class FrameCaps
+{
+public:
+  virtual ~FrameCaps() = default;
+
+  // A rejecting implementation may provide a minimum configured-capacity
+  // hint. Zero means that no useful size recommendation is available.
+  virtual bool CanUseMode(const FrameMode& mode,
+    uint32_t * requiredSizeMiB = nullptr) const = 0;
+};

idd/LGIdd/transport/ITransport.h

@@ -21,9 +21,10 @@
 #pragma once
 
 #include "transport/DirectFrameBufferMemory.h"
-#include "transport/FrameMemoryLimits.h"
+#include "transport/FrameCaps.h"
 #include "transport/TransportConfig.h"
 
+#include <memory>
 #include <stddef.h>
 #include <stdint.h>
 
@@ -89,7 +90,14 @@ public:
   virtual void RecoveryStatus(
     uint64_t, uint32_t, bool, Recovery, uint32_t) {}
 
-  virtual FrameMemoryLimits GetMemoryLimits() const = 0;
+  // Frame capabilities describe the configured instance, not transient
+  // runtime state. CanUseMode answers are immutable for the returned
+  // object's lifetime, and recreating an instance from the same descriptor
+  // must provide the same capability contract.
+  virtual std::shared_ptr<const FrameCaps> GetFrameCaps() const
+  {
+    return std::shared_ptr<const FrameCaps>();
+  }
   virtual DirectFrameBufferMemory GetDirectMemory() const = 0;
 
   // Component pointers are fixed after Setup and remain valid until Stop.

idd/LGIdd/transport/lgmp/CLGMPFrameCaps.cpp

@@ -0,0 +1,112 @@
+/**
+ * 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/lgmp/CLGMPFrameCaps.h"
+
+#include <d3d12.h>
+#include <limits>
+
+namespace
+{
+  static const uint64_t FRAME_BYTES_PER_PIXEL = 4;
+
+  bool AlignUp(uint64_t value, uint64_t alignment, uint64_t& result)
+  {
+    if (!alignment || (alignment & (alignment - 1)))
+      return false;
+
+    const uint64_t mask = alignment - 1;
+    if (value > (std::numeric_limits<uint64_t>::max)() - mask)
+      return false;
+    result = (value + mask) & ~mask;
+    return true;
+  }
+
+  bool CalculateFrameSize(
+    const FrameMode& mode, uint64_t& frameSize)
+  {
+    frameSize = 0;
+    if (!mode.width || !mode.height || !mode.refreshMilliHz)
+      return false;
+
+    uint64_t pitch;
+    if (!AlignUp((uint64_t)mode.width * FRAME_BYTES_PER_PIXEL,
+        D3D12_TEXTURE_DATA_PITCH_ALIGNMENT, pitch) ||
+        pitch > (std::numeric_limits<uint64_t>::max)() / mode.height)
+      return false;
+
+    frameSize = pitch * mode.height;
+    return true;
+  }
+
+  uint32_t RecommendedSizeMiB(uint64_t requiredSize)
+  {
+    uint64_t sizeMiB = requiredSize / 1048576;
+    if (requiredSize % 1048576)
+      ++sizeMiB;
+
+    uint64_t result = 1;
+    while (result < sizeMiB && result <= UINT32_MAX / 2)
+      result <<= 1;
+    return result < sizeMiB ? UINT32_MAX : (uint32_t)result;
+  }
+}
+
+CLGMPFrameCaps::CLGMPFrameCaps(uint64_t capacity,
+    uint64_t frameMemoryOffset, uint32_t bufferCount) :
+  m_capacity(capacity),
+  m_frameMemoryOffset(frameMemoryOffset),
+  m_bufferCount(bufferCount)
+{
+}
+
+bool CLGMPFrameCaps::CanUseMode(const FrameMode& mode,
+  uint32_t * requiredSizeMiB) const
+{
+  if (requiredSizeMiB)
+    *requiredSizeMiB = 0;
+
+  const uint64_t alignment =
+    D3D12_DEFAULT_RESOURCE_PLACEMENT_ALIGNMENT;
+  uint64_t frameSize;
+  if (!m_frameMemoryOffset || !m_bufferCount ||
+      !CalculateFrameSize(mode, frameSize) ||
+      frameSize > (std::numeric_limits<uint64_t>::max)() - alignment)
+    return false;
+
+  uint64_t frameAllocationSize;
+  uint64_t frameMemoryStart;
+  if (!AlignUp(frameSize + alignment, alignment,
+        frameAllocationSize) ||
+      !AlignUp(m_frameMemoryOffset, alignment, frameMemoryStart) ||
+      frameAllocationSize >
+        ((std::numeric_limits<uint64_t>::max)() - frameMemoryStart) /
+          m_bufferCount)
+    return false;
+
+  const uint64_t requiredSize = frameMemoryStart +
+    frameAllocationSize * m_bufferCount;
+  if (requiredSize <= m_capacity)
+    return true;
+
+  if (requiredSizeMiB)
+    *requiredSizeMiB = RecommendedSizeMiB(requiredSize);
+  return false;
+}

idd/LGIdd/transport/lgmp/CLGMPFrameCaps.h

@@ -20,13 +20,21 @@
 
 #pragma once
 
+#include "transport/FrameCaps.h"
+
 #include <stdint.h>
 
-struct FrameMemoryLimits
+class CLGMPFrameCaps final : public FrameCaps
 {
-  uint64_t capacity          = 0;
-  uint64_t frameMemoryOffset = 0;
-  uint64_t alignment         = 0;
-  uint64_t maxFrameSize      = 0;
-  unsigned bufferCount       = 0;
+private:
+  uint64_t m_capacity;
+  uint64_t m_frameMemoryOffset;
+  uint32_t m_bufferCount;
+
+public:
+  CLGMPFrameCaps(uint64_t capacity, uint64_t frameMemoryOffset,
+    uint32_t bufferCount);
+
+  bool CanUseMode(const FrameMode& mode,
+    uint32_t * requiredSizeMiB = nullptr) const override;
 };

idd/LGIdd/transport/lgmp/CLGMPFrameTransport.cpp

@@ -21,10 +21,13 @@
 #include "transport/lgmp/CLGMPFrameTransport.h"
 
 #include "transport/lgmp/CIVSHMEM.h"
+#include "transport/lgmp/CLGMPFrameCaps.h"
 #include "transport/lgmp/CLGMPHost.h"
 #include "CDebug.h"
 
 #include <cstring>
+#include <memory>
+#include <new>
 
 #pragma warning(push)
 #pragma warning(disable: 4200)
@@ -245,15 +248,11 @@ void CLGMPFrameTransport::DeInit()
   memset(m_frameOwnerQueue, 0, sizeof(m_frameOwnerQueue));
 }
 
-FrameMemoryLimits CLGMPFrameTransport::GetMemoryLimits() const
+std::shared_ptr<const FrameCaps> CLGMPFrameTransport::GetFrameCaps() const
 {
-  FrameMemoryLimits limits;
-  limits.capacity          = m_ivshmem.GetUsableSize();
-  limits.frameMemoryOffset = m_frameMemoryOffset;
-  limits.alignment         = m_alignSize;
-  limits.maxFrameSize      = m_maxFrameSize;
-  limits.bufferCount       = LGMP_Q_FRAME_BUFFER_LEN;
-  return limits;
+  return std::shared_ptr<const FrameCaps>(new (std::nothrow)
+    CLGMPFrameCaps(m_ivshmem.GetUsableSize(), m_frameMemoryOffset,
+      LGMP_Q_FRAME_BUFFER_LEN));
 }
 
 CLGMPFrameTransport::SubscriberSnapshot

idd/LGIdd/transport/lgmp/CLGMPFrameTransport.h

@@ -33,9 +33,11 @@ extern "C" {
 #include "common/KVMFR.h"
 #include "capture/CFrameScheduler.h"
 #include "capture/FramePipeline.h"
-#include "transport/FrameMemoryLimits.h"
+#include "transport/FrameCaps.h"
 #include "transport/IFrameSink.h"
 
+#include <memory>
+
 class CIVSHMEM;
 class CLGMPHost;
 class CLGMPTransport;
@@ -151,7 +153,7 @@ private:
   void SealMemoryLayout();
   bool Setup(size_t alignSize);
   void DeInit();
-  FrameMemoryLimits GetMemoryLimits() const;
+  std::shared_ptr<const FrameCaps> GetFrameCaps() const;
   SubscriberSnapshot SnapshotSubscribers() const;
   void FinalizeSubscribers(
     const SubscriberSnapshot& snapshot, uint64_t now);

idd/LGIdd/transport/lgmp/CLGMPTransport.cpp

@@ -239,9 +239,9 @@ void CLGMPTransport::RecoveryStatus(
     session, serial, active, wireState, wireError);
 }
 
-FrameMemoryLimits CLGMPTransport::GetMemoryLimits() const
+std::shared_ptr<const FrameCaps> CLGMPTransport::GetFrameCaps() const
 {
-  return m_frames.GetMemoryLimits();
+  return m_frames.GetFrameCaps();
 }
 
 DirectFrameBufferMemory CLGMPTransport::GetDirectMemory() const

idd/LGIdd/transport/lgmp/CLGMPTransport.h

@@ -61,7 +61,7 @@ public:
     uint64_t session, uint32_t serial, bool active,
     Recovery state, uint32_t error) override;
 
-  FrameMemoryLimits GetMemoryLimits() const override;
+  std::shared_ptr<const FrameCaps> GetFrameCaps() const override;
   DirectFrameBufferMemory GetDirectMemory() const override;
 
   IFrameSink * FrameSink() override { return &m_frames; }