diff --git a/Directory.Build.targets b/Directory.Build.targets
index e086787dc5..f24ee72ef3 100644
--- a/Directory.Build.targets
+++ b/Directory.Build.targets
@@ -30,13 +30,21 @@
+
-
+
+
+
+
+
diff --git a/src/Microsoft.ML.Mkl.Components/SymSgdClassificationTrainer.cs b/src/Microsoft.ML.Mkl.Components/SymSgdClassificationTrainer.cs
index a56ecda0ba..d83f09e776 100644
--- a/src/Microsoft.ML.Mkl.Components/SymSgdClassificationTrainer.cs
+++ b/src/Microsoft.ML.Mkl.Components/SymSgdClassificationTrainer.cs
@@ -825,7 +825,16 @@ private void CheckLabel(RoleMappedData examples, out int weightSetCount)
private static unsafe class Native
{
//To triger the loading of MKL library since SymSGD native library depends on it.
- static Native() => ErrorMessage(0);
+ //On ARM there is no MKL: SymSgdNative bundles the small CBLAS shim it needs and no
+ //libMklImports is shipped, so skip this call (it would fail to load MklImports).
+ static Native()
+ {
+ if (RuntimeInformation.ProcessArchitecture != Architecture.Arm64 &&
+ RuntimeInformation.ProcessArchitecture != Architecture.Arm)
+ {
+ ErrorMessage(0);
+ }
+ }
internal const string NativePath = "SymSgdNative";
internal const string MklPath = "MklImports";
@@ -834,8 +843,8 @@ private static unsafe class Native
[DllImport(NativePath), SuppressUnmanagedCodeSecurity]
private static extern void LearnAll(int totalNumInstances, int* instSizes, int** instIndices,
- float** instValues, float* labels, bool tuneLR, ref float lr, float l2Const, float piw, float* weightVector, ref float bias,
- int numFeatres, int numPasses, int numThreads, bool tuneNumLocIter, ref int numLocIter, float tolerance, bool needShuffle, bool shouldInitialize,
+ float** instValues, float* labels, [MarshalAs(UnmanagedType.I1)] bool tuneLR, ref float lr, float l2Const, float piw, float* weightVector, ref float bias,
+ int numFeatres, int numPasses, int numThreads, [MarshalAs(UnmanagedType.I1)] bool tuneNumLocIter, ref int numLocIter, float tolerance, [MarshalAs(UnmanagedType.I1)] bool needShuffle, [MarshalAs(UnmanagedType.I1)] bool shouldInitialize,
State* state, ChannelCallBack info);
///
diff --git a/src/Native/CMakeLists.txt b/src/Native/CMakeLists.txt
index 9e3647ede1..8602e9dde6 100644
--- a/src/Native/CMakeLists.txt
+++ b/src/Native/CMakeLists.txt
@@ -265,9 +265,16 @@ if(NOT ${ARCHITECTURE} MATCHES "arm.*")
add_subdirectory(CpuMathNative)
add_subdirectory(FastTreeNative)
add_subdirectory(MklProxyNative)
- # TODO: once we fix the 4 intel MKL methods, SymSgdNative will need to go back in.
add_subdirectory(SymSgdNative)
- endif()
+else()
+ # On ARM, SymSgdNative compiles the small MklImportsArm CBLAS shim directly
+ # (see SymSgdNative/CMakeLists.txt), so we do not build a separate libMklImports here.
+ # SymSGD needs OpenMP, which is unavailable for arm64 on the macOS cross-compilation
+ # runner (it only ships an x86_64 libomp), so SymSgdNative is built on Windows/Linux arm only.
+ if(NOT APPLE)
+ add_subdirectory(SymSgdNative)
+ endif()
+endif()
if(${ARCHITECTURE} MATCHES "[xX].*64")
add_subdirectory(OneDalNative)
diff --git a/src/Native/MklImportsArm/MklImportsArm.c b/src/Native/MklImportsArm/MklImportsArm.c
new file mode 100644
index 0000000000..b0db577a39
--- /dev/null
+++ b/src/Native/MklImportsArm/MklImportsArm.c
@@ -0,0 +1,118 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+// ARM replacement for Intel MKL (libMklImports.so).
+//
+// This provides a small, self-contained libMklImports for arm/arm64 that
+// covers exactly the symbols SymSGD needs, with no external BLAS dependency.
+// That is important because the cross-compilation sysroots used in CI do not
+// ship OpenBLAS (or any system BLAS), so linking against one is not an option.
+//
+// SymSGD uses only four CBLAS routines:
+// * cblas_sdot / cblas_saxpy - dense single-precision dot and AXPY,
+// * cblas_sdoti / cblas_saxpyi - their sparse counterparts (MKL extensions).
+// All four are implemented below as plain C loops. With -O3 the compiler
+// autovectorizes the dense paths to NEON, matching hand-written BLAS closely.
+//
+// MKL DFTI (FFT) functions are stubbed — they are referenced by the managed
+// MKL Components initializer but not used by SymSGD. The stubs return error
+// codes so any actual FFT call fails cleanly rather than crashing.
+
+// The native build is compiled with -fvisibility=hidden, so every symbol that
+// must be visible to SymSgdNative (the CBLAS routines) or to the managed
+// P/Invoke layer (DftiErrorMessage) has to be exported explicitly.
+#if defined(_WIN32)
+#define MKLIMPORTS_EXPORT __declspec(dllexport)
+#else
+#define MKLIMPORTS_EXPORT __attribute__((visibility("default")))
+#endif
+
+// --- Dense BLAS (CBLAS, level 1) ---
+
+MKLIMPORTS_EXPORT float cblas_sdot(const int n, const float *x, const int incx,
+ const float *y, const int incy)
+{
+ float result = 0.0f;
+ if (incx == 1 && incy == 1)
+ {
+ for (int i = 0; i < n; i++)
+ result += x[i] * y[i];
+ }
+ else
+ {
+ int ix = incx < 0 ? (1 - n) * incx : 0;
+ int iy = incy < 0 ? (1 - n) * incy : 0;
+ for (int i = 0; i < n; i++, ix += incx, iy += incy)
+ result += x[ix] * y[iy];
+ }
+ return result;
+}
+
+MKLIMPORTS_EXPORT void cblas_saxpy(const int n, const float a, const float *x, const int incx,
+ float *y, const int incy)
+{
+ if (a == 0.0f)
+ return;
+ if (incx == 1 && incy == 1)
+ {
+ for (int i = 0; i < n; i++)
+ y[i] += a * x[i];
+ }
+ else
+ {
+ int ix = incx < 0 ? (1 - n) * incx : 0;
+ int iy = incy < 0 ? (1 - n) * incy : 0;
+ for (int i = 0; i < n; i++, ix += incx, iy += incy)
+ y[iy] += a * x[ix];
+ }
+}
+
+// --- Sparse BLAS (MKL extensions, not in standard BLAS) ---
+
+MKLIMPORTS_EXPORT void cblas_saxpyi(const int nz, const float a,
+ const float *x, const int *indx, float *y)
+{
+ for (int i = 0; i < nz; i++)
+ y[indx[i]] += a * x[i];
+}
+
+MKLIMPORTS_EXPORT float cblas_sdoti(const int nz, const float *x,
+ const int *indx, const float *y)
+{
+ float result = 0.0f;
+ for (int i = 0; i < nz; i++)
+ result += x[i] * y[indx[i]];
+ return result;
+}
+
+// --- DFTI (FFT) stubs ---
+
+MKLIMPORTS_EXPORT const char* DftiErrorMessage(long status)
+{
+ return "DFTI not available (arm64 MKL shim build)";
+}
+
+MKLIMPORTS_EXPORT long DftiCreateDescriptor(void **h, int precision, int domain, int dim, ...)
+{
+ *h = (void*)0;
+ return -1;
+}
+
+MKLIMPORTS_EXPORT long DftiSetValue(void *h, int param, ...)
+{
+ return -1;
+}
+
+MKLIMPORTS_EXPORT long DftiCommitDescriptor(void *h) { return -1; }
+MKLIMPORTS_EXPORT long DftiComputeForward(void *h, ...) { return -1; }
+MKLIMPORTS_EXPORT long DftiComputeBackward(void *h, ...) { return -1; }
+MKLIMPORTS_EXPORT long DftiFreeDescriptor(void **h)
+{
+ // Match MKL's contract: clear the caller's handle after freeing so callers
+ // that rely on the descriptor being nulled out (e.g. the managed
+ // FreeDescriptor(ref IntPtr) P/Invoke) behave correctly.
+ if (h != (void*)0)
+ *h = (void*)0;
+ return 0;
+}
diff --git a/src/Native/Native.proj b/src/Native/Native.proj
index 02a95495bf..22a36bd566 100644
--- a/src/Native/Native.proj
+++ b/src/Native/Native.proj
@@ -189,8 +189,10 @@
RelativePath="Microsoft.ML.CpuMath\runtimes\$(PackageRid)\nativeassets\net8.0" />
-
-
+
- [NativeDependencyFact("MklImports")]
+ [NativeDependencyFact("SymSgdNative")]
public void SimpleTrainAndPredictSymSGD()
{
var ml = new MLContext(seed: 1);
diff --git a/test/Microsoft.ML.Tests/TrainerEstimators/SymSgdClassificationTests.cs b/test/Microsoft.ML.Tests/TrainerEstimators/SymSgdClassificationTests.cs
index 9a2d0aaf13..b1597469d6 100644
--- a/test/Microsoft.ML.Tests/TrainerEstimators/SymSgdClassificationTests.cs
+++ b/test/Microsoft.ML.Tests/TrainerEstimators/SymSgdClassificationTests.cs
@@ -13,7 +13,7 @@ namespace Microsoft.ML.Tests.TrainerEstimators
{
public partial class TrainerEstimators
{
- [NativeDependencyFact("MklImports")]
+ [NativeDependencyFact("SymSgdNative")]
public void TestEstimatorSymSgdClassificationTrainer()
{
(var pipe, var dataView) = GetBinaryClassificationPipeline();
@@ -27,7 +27,7 @@ public void TestEstimatorSymSgdClassificationTrainer()
Done();
}
- [NativeDependencyFact("MklImports")]
+ [NativeDependencyFact("SymSgdNative")]
public void TestEstimatorSymSgdInitPredictor()
{
(var pipe, var dataView) = GetBinaryClassificationPipeline();