What is csm in bios?

CSM, or Compatibility Support Module, is a feature found in modern BIOS systems that allows the system to boot using legacy BIOS modes. It is typically used to ensure compatibility with older hardware and operating systems that may not support UEFI (Unified Extensible Firmware Interface) booting.

CSM essentially emulates a traditional BIOS environment within a UEFI system, allowing the system to boot using legacy BIOS devices such as older hard drives and optical drives. This can be useful when attempting to install older operating systems that do not support UEFI booting, or when using hardware that lacks UEFI compatibility.

However, enabling CSM can also introduce compatibility issues with newer hardware and software, and may result in slower boot times and reduced performance. As such, it is generally recommended to disable CSM when possible in order to take full advantage of the benefits of UEFI booting.

Overall, CSM can be a useful feature for ensuring compatibility with older hardware and operating systems, but it is important to consider the potential drawbacks and limitations when using it in a modern system.