Gentoo on a VIA C7 Netbook

This chronicles my recent experience building, installing, and configuring Gentoo on a Sylvania gBook (a VIA C7-based netbook).

Hardware:

• CPU: VIA C7-M Ultra Low Power 1.2 GHz
• The BIOS seems to clock the CPU down to 600 MHz before starting the OS. The e_powersaver CPUFreq driver is required to put it back at full speed.
• gcc does not have specific tuning for VIA CPUs. The closest you'll be able to get to CPU-specific object code, is enabling the SSE instruction sets.
• Memory: 1 GB
• Storage: 30GB 3600 RPM HDD
• ide0 is disabled. The hard drive is the ide1 master, so the device for it is /dev/hdc (old IDE drivers) or /dev/sda (VIA PATA driver).
• Display: 7" LCD, 800x480 native. DVI port.
• Graphics: VIA CX700M2 UniChrome PRO II
• Supported reasonably well by the latest openchrome driver. The native panel resolution is available through VBE, so VESA drivers can be used.
• Audio: VIA HDA, integrated speakers and microphone, and headphone and microphone jacks
• Seems to need at least kernel 2.6.25 to work well. Supported by the snd-hda-intel driver (with specific options).
• Haven't tested the internal microphone yet.
• Ethernet: RealTek RTL8139
• Supported by the 8139too driver (NOT 8139cp)
• WiFi: RealTek RTL8187
• Seems to be somewhat unreliable in Linux, though newer kernel versions seem to improve matters.
• It's connected to the USB bus, so high throughput will use a lot of CPU time.
• If the "WiFi" light, next to the power light, is unlit, then the WiFi adapter is disabled and will not appear in the USB device list.
• Touchpad
• Despite an unusual size and arrangement, it seems to be a normal Synaptics touchpad, i.e., a PS/2 input device on the i8042 controller.
• Webcam
• Connected to the USB bus.
• Generic, no vendor ID. Supported by very new versions of the uvcvideo driver. Works with cheese, albeit with a somewhat high CPU load.
• SD/MS card slot
• Connected to the USB bus.
• Can be used as a standard USB mass storage device.

Installation

This machine boots readily from an external (USB) CD/DVD drive, so you can pretty much follow the normal Gentoo x86 install guide. I chose to setup an x86 chroot on a fast machine (a dual-core amd64 box) and build the majority of the packages that way; as long as the build host supports the same CFLAGS as the target host, this should be perfectly safe (and has worked fine so far).

Essentially, I have an external USB hard drive with an LVM volume, where I created a 30 MB logical volume (to mimic the 30 GB drive in the netbook) and "installed" the latest Gentoo i686 stage3. Now I can build binary packages on a fast machine with fast RAID disks, and then emerge them later on the netbook. Whether you use LVM or an internal drive for this purpose, you can either scp/rsync the resulting packages to the netbook drive (or just plug the external drive in) or you can use NFS to export some (or all) of your portage tree on your local network (make sure you have "buildpkg" set in your FEATURES)..

Following a few other resources I found on the IntarWeb, I used this for my CFLAGS on the C7:

CFLAGS="-march=i686 -mmmx -msse -msse2 -msse3 -Os -pipe -fomit-frame-pointer"

See the full make.conf file here. There seem to be some odd hardware issues with this machine; see the kernel section for more details.

A few netbook-specific installation tips:

• Either don't make a separate /boot partition, or don't put it as the first partition on the disk (if you do, it won't boot). I made the following three partitions, where sda3 is /boot, and it works fine:

  
  # fdisk -l /dev/sda
  
  Disk /dev/sda: 30.0 GB, 30005821440 bytes
  255 heads, 63 sectors/track, 3648 cylinders
  Units = cylinders of 16065 * 512 = 8225280 bytes
  Disk identifier: 0xdd6cdd6c
  
     Device Boot      Start         End      Blocks   Id  System
  /dev/sda1   *           1        3488    28017328+  83  Linux
  /dev/sda2            3489        3644     1253070   82  Linux swap / Solaris
  /dev/sda3            3645        3648       32130   83  Linux
        

Kernel Config

• Use the provided kernel config for either vanilla-sources or the acpi-sources below (the config should also apply to gentoo-sources) by copying the file to your kernel source dir as .config and then run "make oldconfig." The correct options are already set for you, but include the following device settings:
  • VIA C7 Enhanced PowerSaver - you need this for setting the full CPU speed (find it under the CPU frequency scaling in the ACPI section). You also need the legacy /proc power options, but not apm. Can be modules.
  • Realtek 8187 USB support and generic Wireless LAN support; can be modules.
  • RealTek RTL-8129/8130/8139 PCI Fast Ethernet Adapter support; can be modules.
  • Userspace VESA VGA graphics support - this is compiled directly into the kernel (not as a module) and no other framebuffer drivers are enabled. The VESA driver can't seem to handle the right VBE modes, and the VIA driver is even worse. If you want the proper console resolution (and a working console once X starts) then you'll need this. See below for grub and splash options.
  • VIA PATA support - This is compiled into the kernel, along with the required SCSI disk drivers, etc (the old ATA/ATAPI/MFM/RLL support is completely disabled).
  • Input Device Support - Here I compiled all the relevant drivers directly into the kernel, including atkbd, evdev, the i8042 PC Keyboard controller, and Raw access to serio ports (psmouse is still a module so it's a bit easier to pass options to it).
  • USB Support - pretty much whatever you need, in addition to the required VIA drivers for UHCI and EHCI. Although you may find some laptop kernel configs that enable the "USB selective suspend/resume and wakeup" option, don't enable it on this hardware as it causes random lockups of the i8042 input devices (or worse), as well as hard lockups when certain USB devices are connected (such as a GPS puck receiver).
• This is pretty much the minimum boot configuration needed for the right console resolution; in fact, without it you're likely to get nothing but squiggly lines on the other VTs once X takes over. Note the kernel line should be one long line:

  title=Gentoo 2.6.29-acpi test (uvesafb, no splash)
          root (hd0,2)
          kernel /boot/vmlinuz-2.6.29-acpi root=/dev/sda1 screen=800x480 video=uvesafb:800x480-16@60
        

  Remember the root line above points to sda3 (i.e., my /boot partition). Modify it to match your setup.
• The standard Alsa configuration works fine after you adjust the mixer controls; it may need additional module options to get the correct behavior when the headphone/mic jacks are used.
• Xorg also works fine; the openchrome driver actually does DRI correctly, but there are some drawing artifacts. The old via driver has never been very good, and there's always vesa or fbdev. If you use the openchrome driver, don't enable the ShadowFB option, or your 3D acceleration will fallback from hardware to software. The touchpad requires an InputDevice section for proper config, or you could try a custom hal .fdi file instead. Here's my Xorg config file. Seems like xorg is ignoring the synaptics config in favor of hal. Looks like I'll need that custom .fdi file after all...

Binary Packages

If for some reason you need a binary package for this machine, you can get them here. They may be useful if you have a C7 netbook with only a flash drive whether you run Gentoo or not, since the Gentoo binary package is just a .tbz2 file you can untar directly to "/".

ACPI kernel ebuild

Since a working ACPI configuration (including BIOS settings) is pretty much required for most hardware to function properly these days, I made a patched vanilla sources ebuild a while back (mostly because the latest acpi patch release will only apply to the vanilla kernel source, and even then with some effort). The C7 netbook hardware appears to be the most stable on the patched acpi-sources, at least compared to the straight vanilla-sources or gentoo-sources.

• You can find the latest of the acpi-sources ebuilds in my local portage overlay, all of which include the working hunks of the current ACPI patch release for that particular kernel version, along with the (optional) c7-temp lm_sensor module patch.
• You can still download the 2.6.29 acpi-soures ebuild and patch as a tarball here: 2.6.29-acpi-sources ebuild and 2.6.29-acpi-sources patch. Unpack the ebuild in your local portage overlay and place the patch in your distfiles, generate a new manifest, etc.

Although the lm_sensors script will detect the C7 sensor interface, the module is not part of any mainstream kernel source. Use the above patch to add a sensor for temperature and core voltage (sorry, that's all the driver currently implements, and I have no idea if there's a fan interface, since the lm_sensors fancontrol widget reports nothing recognized).

You can also use the above kernel config with gentoo-sources, and follow the normal fbsplash instructions. I had to make my own splash config for the 800x480 resolution, but it works as long as your images are the correct size, etc. I modified the images provided with the emergence theme to the proper sizes and it looks very nice. I'll update this page if the gentoo-sources kernel appears to be stable with the latest config. The acpi-sources kernel is the current winner for stability...

Overall, the optimized binaries run pretty fast; lxde is snappy, and even a base Gnome install isn't bad... I haven't tried OpenOffice yet, but I wasn't planning on doing any real work on this machine, mostly web browsing, photos, and GPS. I'll see how well ekiga works with the onboard camera once I get a few other things sorted out.

last update: 10/25/2009 12:16