Kernel Log: Coming in 3.9 (Part 2)
As planned, the Linux developers have removed the CONFIG_EXPERIMENTAL kernel configuration option (1, 2). Experimental features could originally only be activated during kernel building if this option was enabled. However, the kernel developers often forgot to remove the CONFIG_EXPERIMENTAL dependency once features had matured. Kernel builders spent many years having to enable the CONFIG_EXPERIMENTAL options, almost as a default, in order to build a kernel for modern hardware components and distributions – the kernel developers have picked up on that and are now dropping this approach. The status of truly experimental features is now only indicated in the help texts that are displayed during configuration and in additions such as "(EXPERIMENTAL)" to the short descriptions; an example can be found in the configuration help text for the Btrfs filesystem.
Kernel Log penguin Linux 3.9 will support a "lightweight suspend" or "suspend freeze" mode that will cause the kernel to send all hardware components into their deepest sleep state. Unlike suspend-to-RAM (ACPI S3), this feature doesn't power down the components so they are quicker to resume operation when they are needed. While the resulting power consumption will be higher than with suspend-to-RAM, it is still designed to be lower than during the normal idle state because the processor can sleep longer and more deeply.