July 7, 2003

Centrino Laptops Becoming Popular Among Linux Geeks

- by Werner Heuser -
Three months after Intel has released
their new technology, 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.

Centrino(TM) consists of three parts: a Pentium M processor, a chipset, and
a wireless module from Intel. Let's see how these parts are supported
under Linux so far:

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 series.
The patches from ACPI4Linux are also highly
recommended. Robert Freund has written a concise
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. Because suspend to RAM is not
supposed to be supported in 2.4 Kernels, you may use
software suspend as a workaround.

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
. But the Pentium-M CPU may come with other graphic chipsets too, e.g.
from ATI, nVIDIA or Trident.

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
to ask Intel to provide Linux support for this feature. As a 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 Ts'o has written a
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.

For an official statement from Intel about Linux support, see their
OS compatibility survey.

If you want to get all the mentioned Kernel patches running smoothly,
try to get the sources from the

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.)

Werner Heuser is founder of
TuxMobil - Linux on Mobile Computers
His Linux-Mobile-Guide, the Linux-Infrared-HOWTO,
the Linux-Ecology-HOWTO as well as surveys about UniX on mobile hardware and software
for mobile users are provided there. As Debian GNU/Linux maintainer he
packages programms related to laptop>s and PDAs. Also he maintains the
"Unofficial" Debian Laptop Proposal.


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