What Not To Expect From The Linux 2.6.40 Kernel

Since the release of the Linux 2.6.39 kernel on Thursday, Linus Torvalds opened the merge window for the Linux 2.6.40 kernel and it will stay open until month's end. While the 2.6.40 kernel will bring several open-source graphics driver improvements (performance improvements, Intel Ivy Bridge support NVIDIA Optimus, etc), new hardware enablement, and other enhancements, there's a few features that you will not find in this next major Linux kernel release.

- The Reiser4 file-system still has not been proposed for integration into the mainline Linux kernel tree. As I mentioned in an exclusive Reiser4 report back in January, the developers are basically waiting for some vendor to stand behind this file-system before it would likely be accepted upstream. However, with Btrfs coming along nicely, finding a vendor to get in bed with Reiser4 is a difficult feat.
- The VIA KMS driver with TTM support still isn't ready to be merged into the mainline Linux kernel. There's working code floating about for kernel mode-setting with some VIA integrated graphics hardware, but there's been no talk of it in recent weeks and it doesn't appear ready to move forward at this time.
- Introduced in the Linux 2.6.39 kernel was a basic open-source KMS driver for Intel Poulsbo within the kernel's staging tree. This kernel driver lacked acceleration support (and there's also no open-source user-space acceleration code) and unfortunately with the Linux 2.6.40 kernel it doesn't look like much will change with this open-source driver.
- Along the same lines as Poulsbo, there still is no open-source upstream kernel driver for other PowerVR SGX hardware from Imagination Technologies. The Free Software Foundation deemed creating a reverse-engineered PowerVR driver for Linux to be a high priority, but there's no active ongoing work towards reaching this goal. Fortunately, something good will soon be happening, but not to be found in the Linux 2.6.40 cycle.
- Still on the graphics spiel, the Nouveau driver with its GeForce 400/500 Fermi support still doesn't have any "free" firmware to ship with the open-source driver or any auto-generating firmware replacement. For the time being, the Fermi GPU firmware must be manually extracted by first running the NVIDIA binary blob and the result is not legally re-distributable. Nouveau developers worked around these problems with previous generations of GeForce/Quadro hardware, but they're still working it out for Fermi. The Nouveau kernel driver does at least support kernel mode-setting without this firmware/micro-code, but it's without accelerated support.
- Also with the Nouveau driver, the developers are still hard at work on figuring out fan control and proper power management support.
- The kernel-side bits to open-source multi-GPU rendering.
- With the open-source Radeon kernel driver, there still is not the bits in place yet for implementing Hyper-Z and Radeon HD 5000/6000 series HDMI audio support, among other features and many wish-list items.

If there's anything else you were hoping to see pushed into the Linux 2.6.40 kernel that doesn't appear to be queued up or has been communicated that it won't be ready in time, share with us in the forums.