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Revamped graphics

Nearly nine months after the initial major announcement, the kernel development team have now integrated support for kernel-based mode setting (KMS) for newer Intel graphics hardware into the main Linux development tree (e.g. 1, 2, 3). This technology means that the kernel is now taking on many of the graphics hardware control functions previously performed by X Server, such as taking responsibility for setting screen resolution. The switch between text console and X Server – e.g. when X Server is first launched during booting – is significantly faster as a result of KMS and should no longer be affected by the flicker or blank screens previously seen during this switch.

Kernel-based mode setting should bring down the curtain on a number of occasional problems caused by conflicts between the VGA console, frame buffer driver, Direct Rendering Manager (DRM) and various userspace programs, including X Server, when accessing graphics hardware. With KMS, X Server can now run without root privileges and the kernel now takes care of all re-initialisation of the graphics hardware when waking from suspend mode, which should improve reliability when using suspend.

To prevent X Server and the kernel squabbling over hardware, X Server and its graphics driver must also support KMS. As Dave Airlie, the X Server and kernel developer responsible for the kernel DRM code, emphasises in his request to pull the collection of patches he has assembled, these components are still under development and KMS is currently still aimed at developers – KMS should not be activated in the kernel set-up without appropriate userspace support. The code is now available, but a few teething troubles should be expected. Setting it up is also far from straightforward.

Better networked

Changes to the Wi-Fi stack activate support for operation as an access point (AP), which has long been in the kernel but deactivated till now (1, 2, documentation). The kernel does not carry out the actual AP administration functions itself, leaving this to the latest version of hostapd. The WLAN drivers also have to support AP mode – which is not the case for the kernel drivers for the Intel WLAN modules installed in Centrino laptops, for example. The 2.6.29 development cycle has seen the developers add AP mode support to the ath5k and p54 WLAN drivers (1, 2). Kernel hackers have also added support for the Atheros AR9285 WLAN chip to the Ath9k WLAN driver, which has long been AP-capable (1, 2).

A new feature for LAN drivers is the generic receive offload (GRO) infrastructure (LWN.net article). Also new are the smsc911x LAN drivers for SMSC's LAN911x and LAN921x LAN chips, the smsc9420 drivers for the same vendor's 100 Mbit LAN9420 chip and the new atl1c driver for L1C series Atheros Gigabit Ethernet chips.

Next: On the move

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