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Centrino

Intels Centrino(TM) technology consists of three parts: a Pentium M processor, a chipset, and a wireless module. Let's see how these parts are supported under Linux so far. For an official statement from Intel about Linux support, see their OS compatibility survey.

CPU: Pentium-M

According to Intel's OS compatibility survey , the Pentium M processor (earlier codenamed Banias) is supported. Some Kernel patches (PCI IDs, AGP GART) are available in the Alan Cox 2.4.x Kernel series . The patches from the ACPI project are also highly recommended. Robert Freund has written a concise HOWTO about controlling ACPI Centrino(TM) features via software in Linux. He describes how to control CPU frequency and other energy saving modes, as well how to get information about the battery state.

Chipset: 855PM/GM

The Intel 855 chipset family (earlier codenamed Odem) is designed to deliver better performance at lower power. The Intel 855PM Chipset is a discrete memory controller hub. The Intel 855GM Chipset is an integrated graphics and memory controller hub. Intel provides the Extreme Graphics driver for Linux, which includes AGP GART and DRM kernel modules as a binary file. But the Pentium-M CPU may come accompanied with other graphic chipsets too, e.g. from ATI, nVIDIA or Trident.

Wireless LAN: PRO/wireless 2100 LAN Mini-PCI Adapter

For the PRO/Wireless 2100 LAN Mini-PCI Adapter, which currently implements WLAN standard 802.11b, Intel does not yet provide drivers, and technical documentation, which would make it possible to write drivers, is not available. You may use this form to ask Intel to provide Linux support for this feature. Intel's attitude has changed recently, see their announcement for WLAN drivers, but it is still uncertain when this driver will arrive and whether it will be Open Source or not. So you should consider to the Intel Support of Centrino Under Linux petition.

There are different solutions though: NDIS wrappers and miniPCI cards with Linux support.

Some vendors refuses to release technical specifications or even a binary Linux driver for their WLAN cards. NDIS wrappers try to solve this by making a kernel module that can load NDIS (Microsoft-Windows Network Driver Interface Specification) drivers. Currently there are two implemantions available. The commercial Linuxant Driverloader supports a broad range of chipsets including Intel's PRO/Wireless 2100 LAN Mini-PCI Adapter. There is also an Open Source solution by Pontus Fuchs. ndiswrapper does not yet support the Intel chipset. But there is a fair chance that somebody will hack this in, too.

As another workaround you may use a miniPCI WLAN card. These cards are difficult to get, but some desktop WLAN PCI cards contain miniPCI cards. Often it is a tedious task to build them into a laptop. Kernel maintainer Theodore Tytso has written a manual about achieving this task. You may also use a wireless PCMCIA or CF card instead. This solution may provide more flexibility, because you may use a PCMCIA or CF card in different devices and choose the Linux driver of your choice. You may also extend the wireless range by adding antennas to some cards. For Linux compatibility there is the TuxMobil PCMCIA/CF Card Survey. In the future, manufacturers will probably offer alternative miniPCI solutions. DELL is already doing so for their Latitude D series.

Conclusion

Though Linux support is not yet complete, some features of the Centrino(TM) technology already make it worthwhile to take into account when buying your next laptop. Though the new CPUs are named so similarly to existing ones that some people mix them up, they are completely different inside. Compared to the Pentium-4 Mobile CPU, the Pentium-M will allow a smaller form factor for laptops, making them more portable and lighter. Because of their higher clockspeed, the Pentium-4 CPUs have produced too much heat to build them into slimline notebook cases. Therefore, very flat notebooks have only been available from Apple or with a Pentium III Mobile CPU. Also, the battery power the Pentium-M consumes for a given level of performance will decrease, but I do not have a benchmark about how much the savings actually are yet. PENN Computing offers a nice comparison of Pentium-M and Pentium-4 Mobile. Note: The character M in Pentium-M suggests "mobile". Therefore some people mix this kind of CPU with the mobile issues of the Pentium-III/Pentium-4 CPU.

Laptops based on the Centrino(TM) features are already very popular in the Linux community. For almost all Centrino based laptops from different manufacturers there are installation reports available at TuxMobil.