diff --git a/.ci/scripts/build-qnn-direct-sdk.sh b/.ci/scripts/build-qnn-direct-sdk.sh
new file mode 100755
index 00000000000..4eccd0115f4
--- /dev/null
+++ b/.ci/scripts/build-qnn-direct-sdk.sh
@@ -0,0 +1,33 @@
+#!/bin/bash
+# Copyright (c) Qualcomm Innovation Center, Inc.
+# All rights reserved
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+set -eux
+
+source "$(dirname "${BASH_SOURCE[0]}")/../../backends/qualcomm/scripts/install_qnn_sdk.sh"
+
+setup_android_ndk
+install_qnn
+install_hexagon_sdk
+
+bash backends/qualcomm/scripts/build.sh \
+    --build_direct_mode 3 --soc_model SM8750 \
+    --skip_x86_64 --skip_linux_android \
+    --release
+
+ARTIFACT="build-direct/backends/qualcomm/libqnn_executorch_backend.so"
+if [ ! -f "${ARTIFACT}" ]; then
+    echo "ERROR: direct-mode build did not produce ${ARTIFACT}" >&2
+    exit 1
+fi
+
+MAX_SIZE_BYTES=$((200 * 1024))
+ARTIFACT_SIZE=$(stat -c%s "${ARTIFACT}")
+if [ "${ARTIFACT_SIZE}" -gt "${MAX_SIZE_BYTES}" ]; then
+    echo "ERROR: ${ARTIFACT} is ${ARTIFACT_SIZE} bytes, exceeds ${MAX_SIZE_BYTES}-byte (200 KiB) limit" >&2
+    exit 1
+fi
+echo "PASSED: direct-mode build produced ${ARTIFACT} (${ARTIFACT_SIZE} bytes, under ${MAX_SIZE_BYTES}-byte limit)"
diff --git a/.github/workflows/pull.yml b/.github/workflows/pull.yml
index 3ead9e6a49c..0ecab2c11b5 100644
--- a/.github/workflows/pull.yml
+++ b/.github/workflows/pull.yml
@@ -948,6 +948,25 @@ jobs:
         PYTHON_EXECUTABLE=python bash .ci/scripts/build-qnn-sdk.sh
         PYTHON_EXECUTABLE=python bash .ci/scripts/test_model.sh ${{ matrix.model }} "cmake" "qnn"
 
+  test-qnn-direct-build-linux:
+    name: test-qnn-direct-build-linux
+    uses: pytorch/test-infra/.github/workflows/linux_job_v2.yml@main
+    permissions:
+      id-token: write
+      contents: read
+    with:
+      runner: linux.2xlarge
+      docker-image: ci-image:executorch-ubuntu-22.04-qnn-sdk
+      submodules: 'recursive'
+      ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
+      timeout: 30
+      script: |
+        # The generic Linux job chooses to use base env, not the one setup by the image
+        CONDA_ENV=$(conda env list --json | jq -r ".envs | .[-1]")
+        conda activate "${CONDA_ENV}"
+        PYTHON_EXECUTABLE=python bash .ci/scripts/setup-linux.sh --build-tool cmake
+        PYTHON_EXECUTABLE=python bash .ci/scripts/build-qnn-direct-sdk.sh
+
   test-qnn-testsuite-linux:
     name: test-qnn-testsuite-linux
     permissions:
diff --git a/CMakeLists.txt b/CMakeLists.txt
index bf6701123df..721880ea1d1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -49,17 +49,6 @@ cmake_minimum_required(VERSION 3.24)
 
 set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR})
 
-# Hexagon toolchain with release build complains about code in third party
-# libraries.
-if("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "Hexagon" AND "${CMAKE_BUILD_TYPE}"
-                                                     STREQUAL "Release"
-)
-  add_compile_options(
-    -Wno-error=format -Wno-error=implicit-int-conversion
-    -Wno-error=unused-variable -Wno-error=unused-function
-  )
-endif()
-
 # --- ExecuTorch Version ---
 # Parse version from version.txt (single source of truth)
 file(READ "${EXECUTORCH_ROOT}/version.txt" ET_VERSION_STRING)
@@ -90,6 +79,18 @@ project(executorch
         VERSION "${ET_VERSION_MAJOR}.${ET_VERSION_MINOR}.${ET_VERSION_PATCH}"
 )
 
+# Hexagon toolchain with release build complains about code in third party
+# libraries. Must come after project(), which runs the toolchain file that sets
+# CMAKE_SYSTEM_PROCESSOR, and before add_subdirectory(third-party).
+if("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "Hexagon" AND "${CMAKE_BUILD_TYPE}"
+                                                     STREQUAL "Release"
+)
+  add_compile_options(
+    -Wno-error=format -Wno-error=implicit-int-conversion
+    -Wno-error=unused-variable -Wno-error=unused-function
+  )
+endif()
+
 message(
   STATUS
     "ExecuTorch version: ${ET_VERSION_MAJOR}.${ET_VERSION_MINOR}.${ET_VERSION_PATCH}"
diff --git a/backends/qualcomm/scripts/build.sh b/backends/qualcomm/scripts/build.sh
index 498bf924921..b0ef5a8ddbd 100755
--- a/backends/qualcomm/scripts/build.sh
+++ b/backends/qualcomm/scripts/build.sh
@@ -48,6 +48,7 @@ usage() {
   echo "e.g.: executorch$ ./backends/qualcomm/scripts/build.sh --skip_x86_64"
   echo ""
   echo "Direct mode: Use --build_direct_mode <dsp_type> --soc_model <model> to enable."
+  echo "<dsp_type> id is mapped to Hexagon SDK dsp id. Refer to Hexagon SDK for more info."
   echo "You can choose either LPAI (ADSP) or CDSP (HTP) as the target DSP:"
   echo "  LPAI (ADSP): dsp_type=0"
   echo "  CDSP (HTP):  dsp_type=3"
diff --git a/backends/qualcomm/scripts/build_utils.sh b/backends/qualcomm/scripts/build_utils.sh
index 81a7f2d9f2d..91651deb7ec 100644
--- a/backends/qualcomm/scripts/build_utils.sh
+++ b/backends/qualcomm/scripts/build_utils.sh
@@ -21,15 +21,15 @@ import sys, os
 devnull = open(os.devnull, 'w')
 old_stdout = sys.stdout
 sys.stdout = devnull
-from executorch.backends.qualcomm.utils.utils import get_soc_to_htp_arch_map
+from executorch.backends.qualcomm.serialization.qc_schema import _soc_info_table
 sys.stdout = old_stdout
-m = get_soc_to_htp_arch_map()
+m = {soc.name: info.htp_info.htp_arch for soc, info in _soc_info_table.items()}
 if '${soc_model}' not in m:
     sys.exit(1)
 print(m['${soc_model}'].value)
 " 2>/dev/null) || {
         echo "Error: SoC model '${soc_model}' not found in HTP arch map."
-        echo "Check supported models in executorch/backends/qualcomm/utils/utils.py get_soc_to_htp_arch_map()."
+        echo "Check supported models in executorch/backends/qualcomm/serialization/qc_schema.py _soc_info_table."
         exit 1
     }
 
@@ -39,15 +39,19 @@ import sys, os
 devnull = open(os.devnull, 'w')
 old_stdout = sys.stdout
 sys.stdout = devnull
-from executorch.backends.qualcomm.utils.utils import get_soc_to_lpai_hw_ver_map
+from executorch.backends.qualcomm.serialization.qc_schema import _soc_info_table
 sys.stdout = old_stdout
-m = get_soc_to_lpai_hw_ver_map()
+m = {
+    soc.name: info.lpai_info.lpai_hardware_version
+    for soc, info in _soc_info_table.items()
+    if info.lpai_info is not None
+}
 if '${soc_model}' not in m:
     sys.exit(1)
 print(m['${soc_model}'].value)
 " 2>/dev/null) || {
             echo "Error: SoC model '${soc_model}' not found in LPAI hardware version map."
-            echo "Check supported models in executorch/backends/qualcomm/utils/utils.py get_soc_to_lpai_hw_ver_map()."
+            echo "Check supported models in executorch/backends/qualcomm/serialization/qc_schema.py _soc_info_table."
             exit 1
         }
     fi
diff --git a/backends/qualcomm/scripts/install_qnn_sdk.sh b/backends/qualcomm/scripts/install_qnn_sdk.sh
index 7921b48da2f..f7e8ccab184 100644
--- a/backends/qualcomm/scripts/install_qnn_sdk.sh
+++ b/backends/qualcomm/scripts/install_qnn_sdk.sh
@@ -109,6 +109,83 @@ install_qnn() {
   echo "Set QNN_SDK_ROOT=${QNN_SDK_ROOT}"
 }
 
+# Install the Hexagon SDK required for direct-mode CI builds.
+install_hexagon_sdk() {
+  # Check if already configured externally and valid.
+  if [ -n "${HEXAGON_SDK_ROOT:-}" ] && [ -d "${HEXAGON_SDK_ROOT:-}" ] \
+     && [ -n "${HEXAGON_TOOLS_ROOT:-}" ] && [ -d "${HEXAGON_TOOLS_ROOT:-}" ]; then
+    echo "Hexagon SDK already set to ${HEXAGON_SDK_ROOT} - skipping installation"
+    return
+  fi
+
+  echo "Start installing Hexagon SDK v${HEXAGON_SDK_VERSION} (tools v${HEXAGON_TOOLS_VERSION})"
+  HEXAGON_INSTALLATION_DIR="/tmp/hexagon-sdk"
+  HEXAGON_SDK_DIR="${HEXAGON_INSTALLATION_DIR}/Hexagon_SDK/${HEXAGON_SDK_VERSION}"
+  HEXAGON_TOOLS_DIR="${HEXAGON_SDK_DIR}/tools/HEXAGON_Tools/${HEXAGON_TOOLS_VERSION}"
+
+  # Return if already exist
+  if [ -d "${HEXAGON_SDK_DIR}" ] && [ -d "${HEXAGON_TOOLS_DIR}" ]; then
+    echo "Hexagon SDK already installed at ${HEXAGON_SDK_DIR}"
+    export HEXAGON_SDK_ROOT="${HEXAGON_SDK_DIR}"
+    export HEXAGON_TOOLS_ROOT="${HEXAGON_TOOLS_DIR}"
+    return
+  fi
+
+  mkdir -p "${HEXAGON_INSTALLATION_DIR}"
+
+  HEXAGON_ZIP_FILE="Hexagon_SDK_Linux.zip"
+  # Match install_qnn's retry shape: --fail rejects HTTP errors,
+  # --retry-all-errors retries transport failures, `unzip -t` validates the
+  # archive, and the SHA-256 check pins the exact bytes we tested against. All
+  # are inside the retry condition so a truncated or wrong-content download is
+  # re-fetched rather than killing the job.
+  HEXAGON_DOWNLOAD_MAX_ATTEMPTS=5
+  for attempt in $(seq 1 ${HEXAGON_DOWNLOAD_MAX_ATTEMPTS}); do
+    rm -f "/tmp/${HEXAGON_ZIP_FILE}"
+    if curl --fail --retry 3 --retry-delay 5 --retry-connrefused --retry-all-errors \
+         -Lo "/tmp/${HEXAGON_ZIP_FILE}" "${HEXAGON_SDK_ZIP_URL}" \
+       && unzip -tq "/tmp/${HEXAGON_ZIP_FILE}" \
+       && echo "${HEXAGON_SDK_ZIP_SHA256}  /tmp/${HEXAGON_ZIP_FILE}" | sha256sum -c -; then
+      break
+    fi
+    ls -l "/tmp/${HEXAGON_ZIP_FILE}" 2>&1 || true
+    if [ "${attempt}" = "${HEXAGON_DOWNLOAD_MAX_ATTEMPTS}" ]; then
+      echo "ERROR: Hexagon SDK download failed after ${attempt} attempts" >&2
+      exit 1
+    fi
+    echo "Hexagon SDK download attempt ${attempt} failed; retrying in $((attempt * 10))s..."
+    sleep $((attempt * 10))
+  done
+  echo "Finishing downloading Hexagon SDK."
+
+  unzip -qo "/tmp/${HEXAGON_ZIP_FILE}" -d "${HEXAGON_INSTALLATION_DIR}"
+  echo "Finishing unzip Hexagon SDK."
+
+  export HEXAGON_SDK_ROOT="${HEXAGON_SDK_DIR}"
+  export HEXAGON_TOOLS_ROOT="${HEXAGON_TOOLS_DIR}"
+
+  # Verify the unzipped layout matches what build.sh and the QNN CMake
+  # files actually consume. If any of these are missing, a future SDK
+  # release likely changed the directory shape; updating
+  # HEXAGON_SDK_VERSION / HEXAGON_TOOLS_VERSION in qnn_config.sh (or the
+  # extraction layout below) is the fix.
+  for hexagon_required_path in \
+      "${HEXAGON_SDK_ROOT}" \
+      "${HEXAGON_SDK_ROOT}/build/cmake/hexagon_toolchain.cmake" \
+      "${HEXAGON_TOOLS_ROOT}" \
+      "${HEXAGON_TOOLS_ROOT}/Tools/target/hexagon"; do
+    if [ ! -e "${hexagon_required_path}" ]; then
+      echo "[Hexagon] ERROR: expected path not found: ${hexagon_required_path}" >&2
+      echo "[Hexagon] Hexagon SDK ${HEXAGON_SDK_VERSION} or tools ${HEXAGON_TOOLS_VERSION} layout differs from what we pinned." >&2
+      ls -la "$(dirname "${hexagon_required_path}")" >&2 || true
+      exit 1
+    fi
+  done
+
+  echo "Set HEXAGON_SDK_ROOT=${HEXAGON_SDK_ROOT}"
+  echo "Set HEXAGON_TOOLS_ROOT=${HEXAGON_TOOLS_ROOT}"
+}
+
 setup_libcpp() {
   clang_version=$1
   LLVM_VERSION="14.0.0"
diff --git a/backends/qualcomm/scripts/qnn_config.sh b/backends/qualcomm/scripts/qnn_config.sh
index 938eb0d3007..cbdf2af7630 100644
--- a/backends/qualcomm/scripts/qnn_config.sh
+++ b/backends/qualcomm/scripts/qnn_config.sh
@@ -8,3 +8,11 @@
 # QNN SDK Configuration
 QNN_VERSION="2.37.0.250724"
 QNN_ZIP_URL="https://softwarecenter.qualcomm.com/api/download/software/sdks/Qualcomm_AI_Runtime_Community/All/${QNN_VERSION}/v${QNN_VERSION}.zip"
+
+# Hexagon SDK Configuration (used only by direct-mode CI build).
+# HEXAGON_TOOLS_VERSION must match the toolchain shipped inside HEXAGON_SDK_VERSION.
+HEXAGON_SDK_VERSION="6.5.0.0"
+HEXAGON_TOOLS_VERSION="19.0.07"
+HEXAGON_SDK_ZIP_URL="https://apigwx-aws.qualcomm.com/qsc/public/v1/api/download/software/sdks/Hexagon_SDK/Linux/Debian/${HEXAGON_SDK_VERSION}/Hexagon_SDK_Linux.zip"
+# SHA-256 of the downloaded zip. Recompute and update when HEXAGON_SDK_VERSION changes. Command to gen followin sha: sha256sum Hexagon_SDK_Linux.zip
+HEXAGON_SDK_ZIP_SHA256="668626f75c38ce1ca993768953db9bf4b632753c3e32ed8363a8287e3aaffc9a"
diff --git a/extension/data_loader/mman.h b/extension/data_loader/mman.h
index a7a335961c8..9d3ee4be5aa 100644
--- a/extension/data_loader/mman.h
+++ b/extension/data_loader/mman.h
@@ -48,10 +48,17 @@ ET_INLINE off_t get_mmap_offset(size_t offset) {
  * Hint the kernel to prefetch pages eagerly and to optimize for sequential
  * reads. Intended to reduce page-fault stutter during model initialization
  * when the caller does not want to mlock the pages into RAM.
+ *
+ * MADV_WILLNEED / MADV_SEQUENTIAL are absent on some POSIX libcs (e.g. the
+ * Hexagon DSP toolchain).
  */
 ET_INLINE void madvise_pages_willneed_sequential(void* addr, size_t len) {
+#ifdef MADV_WILLNEED
   ::madvise(addr, len, MADV_WILLNEED);
+#endif
+#ifdef MADV_SEQUENTIAL
   ::madvise(addr, len, MADV_SEQUENTIAL);
+#endif
 }
 
 /**