docs: update remote faq for unsupported server mode (#7953)

* docs: update remote faq for unsupported server mode

* Review updates

* Update note

* doc: add sample container to prepare crosstool-ng

* Update docs/remote/faq.md

* Update docs/remote/faq.md

* doc: add clause about recommended patchelf version

---------

Co-authored-by: Nick Trogh <[email protected]>

Author: deepak1556

docs/remote/faq.md

@@ -109,7 +109,67 @@ See [Remote Development with Linux](/docs/remote/linux.md) for additional detail
 
 ### Can I run VS Code Server on older Linux distributions?
 
-Starting with VS Code release 1.86.1 (January 2024), the minimum requirements for the build toolchain of the remote server were raised. The prebuilt servers distributed by VS Code are compatible with Linux distributions based on glibc 2.28 or later, for example, Debian 10, RHEL 8, or Ubuntu 20.04. VS Code will still allow users to connect to an OS that is not supported by VS Code (OS that does not provide glibc >= 2.28 and libstdc++ >= 3.4.25) until February 2025. This allows time for you and your companies to migrate to newer Linux distributions. VS Code will show a dialog and banner message when you connect to an OS version that is not supported by VS Code.
+Starting with VS Code release 1.99 (March 2025), the prebuilt servers distributed by VS Code are only compatible with Linux distributions that are based on glibc 2.28 or later. These include for example, Debian 10, RHEL 8, or Ubuntu 20.04.
+
+VS Code will still allow users to connect to an OS that is not supported by VS Code (OSes that don't have glibc >= 2.28 and libstdc++ >= 3.4.25) via the [Remote - SSH](https://aka.ms/vscode-remote/download/ssh) extension, if a sysroot with these required library versions is provided. This approach gives you and your organization more time to migrate to newer Linux distributions.
+
+| VS Code version | Base Requirements | Notes |
+|--------------|-------------------|-------|
+| 1.99.x |  kernel >= 4.18, glibc >=2.28, libstdc++ >= 3.4.25, binutils >= 2.29 | <none> |
+
+> [!IMPORTANT]
+> This approach is a technical workaround and is not an officially supported usage scenario.
+
+Follow these steps to configure your environment for this workaround:
+
+1. Build the sysroot
+
+    We recommend using [Crosstool-ng](https://crosstool-ng.github.io/docs/) to build the sysroot. Here are some example configs that you can start with:
+
+    * [x86_64-gcc-8.5.0-glibc-2.28](https://github.com/microsoft/vscode-linux-build-agent/blob/main/x86_64-gcc-8.5.0-glibc-2.28.config)
+    * [aarch64-gcc-8.5.0-glibc-2.28](https://github.com/microsoft/vscode-linux-build-agent/blob/main/aarch64-gcc-8.5.0-glibc-2.28.config)
+    * [armhf-gcc-8.5.0-glibc-2.28](https://github.com/microsoft/vscode-linux-build-agent/blob/main/armhf-gcc-8.5.0-glibc-2.28.config)
+
+    The following example container can also be used to have an environment with [Crosstool-ng](https://crosstool-ng.github.io/docs/) installed:
+
+    ```docker
+    FROM ubuntu:latest
+
+    RUN apt-get update
+    RUN apt-get install -y gcc g++ gperf bison flex texinfo help2man make libncurses5-dev \
+    python3-dev autoconf automake libtool libtool-bin gawk wget bzip2 xz-utils unzip \
+    patch rsync meson ninja-build
+
+    # Install crosstool-ng
+    RUN wget http://crosstool-ng.org/download/crosstool-ng/crosstool-ng-1.26.0.tar.bz2
+    RUN tar -xjf crosstool-ng-1.26.0.tar.bz2
+    RUN cd crosstool-ng-1.26.0 && ./configure --prefix=/crosstool-ng-1.26.0/out && make && make install
+    ENV PATH=$PATH:/crosstool-ng-1.26.0/out/bin
+    ```
+
+    Once you have an environment with [Crosstool-ng](https://crosstool-ng.github.io/docs/) and the relevant configs prepared, run the following commands to generate the sysroot
+
+    ```sh
+    mkdir toolchain-dir
+    cd toolchain-dir
+    cp <path-to-config-file> > .config
+    ct-ng build
+    ```
+
+2. VS Code server uses [patchelf](https://github.com/NixOS/patchelf) during the installation process to consume the required libraries from the sysroot.
+
+> [!IMPORTANT]
+> patchelf `v0.17.x` is known to cause segfaults with the remote server, we recommend using patchelf `>=v0.18.x`
+
+3. Install the patchelf binary and the sysroot on the remote host
+
+4. Create the following 3 environment variables:
+
+    * **VSCODE_SERVER_CUSTOM_GLIBC_LINKER** path to the dynamic linker in the sysroot (used for `--set-interpreter` option with [patchelf](https://github.com/NixOS/patchelf))
+    * **VSCODE_SERVER_CUSTOM_GLIBC_PATH** path to the library locations in the sysroot (used as `--set-rpath` option with [patchelf](https://github.com/NixOS/patchelf))
+    * **VSCODE_SERVER_PATCHELF_PATH** path to the [patchelf](https://github.com/NixOS/patchelf) binary on the remote host
+
+You can now connect to the remote by using the [Remote - SSH](https://aka.ms/vscode-remote/download/ssh) extension. On successful connection, VS Code will show a dialog and banner message about the connection not being supported.
 
 ### Can I install individual extensions instead of the extension pack?