[Doc]: improve CPU(x86) build-wheel-from-source section (#25617)

Signed-off-by: Kosseila (CloudThrill) <klouddude@gmail.com>

Author: brokedba

docs/getting_started/installation/cpu/x86.inc.md

@@ -20,7 +20,80 @@ vLLM supports basic model inferencing and serving on x86 CPU platform, with data
 # --8<-- [end:pre-built-wheels]
 # --8<-- [start:build-wheel-from-source]
 
---8<-- "docs/getting_started/installation/cpu/build.inc.md"
+Install recommended compiler. We recommend to use `gcc/g++ >= 12.3.0` as the default compiler to avoid potential problems. For example, on Ubuntu 22.4, you can run:
+
+```bash
+sudo apt-get update -y
+sudo apt-get install -y gcc-12 g++-12 libnuma-dev python3-dev
+sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-12 10 --slave /usr/bin/g++ g++ /usr/bin/g++-12
+```
+
+Clone the vLLM project:
+
+```bash
+git clone https://github.com/vllm-project/vllm.git vllm_source
+cd vllm_source
+```
+
+Install the required dependencies:
+
+```bash
+uv pip install -r requirements/cpu-build.txt --torch-backend cpu
+uv pip install -r requirements/cpu.txt --torch-backend cpu
+```
+
+??? console "pip"
+    ```bash
+    pip install --upgrade pip
+    pip install -v -r requirements/cpu-build.txt --extra-index-url https://download.pytorch.org/whl/cpu
+    pip install -v -r requirements/cpu.txt --extra-index-url https://download.pytorch.org/whl/cpu
+    ```
+
+Build and install vLLM:
+
+```bash
+VLLM_TARGET_DEVICE=cpu uv pip install . --no-build-isolation
+```
+
+If you want to develop vLLM, install it in editable mode instead.
+
+```bash
+VLLM_TARGET_DEVICE=cpu uv pip install -e . --no-build-isolation
+```
+
+Optionally, build a portable wheel which you can then install elsewhere:
+
+```bash
+VLLM_TARGET_DEVICE=cpu uv build --wheel
+```
+
+```bash
+uv pip install dist/*.whl
+```
+
+??? console "pip"
+    ```bash
+    VLLM_TARGET_DEVICE=cpu python -m build --wheel --no-isolation
+    ```
+
+    ```bash
+    pip install dist/*.whl
+    ```
+
+!!! example "Troubleshooting"
+    - **NumPy ≥2.0 error**: Downgrade using `pip install "numpy<2.0"`.
+    - **CMake picks up CUDA**: Add `CMAKE_DISABLE_FIND_PACKAGE_CUDA=ON` to prevent CUDA detection during CPU builds, even if CUDA is installed.
+    - `AMD` requies at least 4th gen processors (Zen 4/Genoa) or higher to support [AVX512](https://www.phoronix.com/review/amd-zen4-avx512) to run vLLM on CPU.
+    - If you receive an error such as: `Could not find a version that satisfies the requirement torch==X.Y.Z+cpu+cpu`, consider updating [pyproject.toml](https://github.com/vllm-project/vllm/blob/main/pyproject.toml) to help pip resolve the dependency.
+    ```toml title="pyproject.toml"
+    [build-system]
+    requires = [
+      "cmake>=3.26.1",
+      ...
+      "torch==X.Y.Z+cpu"   # <-------
+    ]
+    ```
+    - If you are building vLLM from source and not using the pre-built images, remember to set `LD_PRELOAD="/usr/lib/x86_64-linux-gnu/libtcmalloc_minimal.so.4:$LD_PRELOAD"` on x86 machines before running vLLM.
 
 # --8<-- [end:build-wheel-from-source]
 # --8<-- [start:pre-built-images]
@@ -57,4 +130,4 @@ docker run --rm \
 
 # --8<-- [end:build-image-from-source]
 # --8<-- [start:extra-information]
-# --8<-- [end:extra-information]
+# --8<-- [end:extra-information]