Prerequisites

• Intel Galileo Board (well, not really needed for the build process, but you want to run the image somewhere, right?). Update the boards' firmware. Older firmware has a bug that prevents booting from SD card.
  
• A computer with a fairly new Linux distribution installed on it. I used Ubuntu 12.04.
• Development tools, GCC compiler, etc. You'll also need 7zip utility. Debian/Ubuntu people do:
  sudo apt-get install build-essential p7zip-full
• 70GB or so available space on the hard drive.
• Fairly fast Internet connection. It is going to download all the sources required for the image from the Internet.
• A few hours to complete the build process. This will depend on the performance of your computer and the Internet connection speed.

Basic Steps to Rebuild The Image

1. Create a directory you'll be using for the build process. Do not use spaces in the directory name. Yocto doesn't like them.
   
2. Download "Board Support Package Sources for Intel Quark" from https://communities.intel.com/community/makers/software/drivers. And copy it to your build directory. In my case the file was named Board_Support_Package_Sources_for_Intel_Quark_v0.7.5.7z.
3. Unzip the file:
   7z x Board_Support_Package_Sources_for_Intel_Quark_v0.7.5.7z
4. Unzip meta-clanton_v0.7.5.tar.gz:
   tar xzvf Board_Support_Package_Sources_for_Intel_Quark_v0.7.5/meta-clanton_v0.7.5.tar.gz
5. Change directory to meta-clanton_v0.7.5:
   cd meta-clanton_v0.7.5
6. Run setup.sh:
   ./setup.sh
7. Source poky/oe-init-build-env script, giving it the build directory (yocto_build) as a parameter:
   source poky/oe-init-build-env yocto_build
8. Run bitbake to build the image:
   bitbake image-full
• Note: image-full - SD card image, image-spi - SPI flash image.
  
9. Wait several hours, and if everything goes well you'll get your image in tmp/deploy/images/ directory. It will include:
• The Linux kernel: bzImage--3.8-r0-clanton-YYYYMMDDhhmmss.bin (YYYYMMDDhhmmss - timestamp indicating the build start time)
  
• Initial RAM FS: core-image-minimal-initramfs-clanton-YYYYMMDDhhmmss.rootfs.cpio.gz
• File system image: image-full-clanton-YYYYMMDDhhmmss.rootfs.ext3
  
• Kernel modules: modules--3.8-r0-clanton-YYYYMMDDhhmmss.tgz (not really needed, they are already in the file system image)
  
• Grub configuration: boot/grub/grub.conf
  
10. Copy these files to SD card renaming files as follows (resulting paths are relative to SD card's root):
• bzImage--3.8-r0-clanton-YYYYMMDDhhmmss.bin -> bzImage
• core-image-minimal-initramfs-clanton-YYYYMMDDhhmmss.rootfs.cpio.gz -> core-image-minimal-initramfs-clanton.cpio.gz
• image-full-clanton-YYYYMMDDhhmmss.rootfs.ext3 -> image-full-clanton.ext3
• boot/grub/grub.conf -> boot/grub/grub.conf
  
• Note that you can keep names or use different names for all files except of the image-full-clanton.ext3, and just update grub.conf with the correct names. The file system image must be named image-full-clanton.ext3 (initramfs will look for that) unless you update the configuration.
11. Insert SD card to your Galileo board, reboot it, and enjoy!

Building Linux Standard Base (LSB) Image

Update local.conf

Comment out uClibc patch for v4l2apps

Create recipe for the image

Copy ../meta-clanton-distro/recipes-core/images/image-full.bb  file to ../meta-clanton-distro/recipes-core/images/image-sdk.bb:

Edit ../meta-clanton-distro/recipes-core/images/image-sdk.bb file. Append packagegroup-core-basic packagegroup-core-lsb kernel-dev to IMAGE_INSTALL:

You might also want to increase root file system size from the 300 MB default to 3 GB or so. If configured as described here image will use about 1.5GB so with 3 GB you'll have plenty of space for other things.

Other Changes

I made a couple more tweaks to the image. First is an update to Galileo kernel patch to fix an issue with CY8C9540A I/O expander. By default intel_cln_gip module configures Intel Quark to use I2C fast mode, and CY8C9540A doesn't want to work with that mode. So the change is to make standard mode default. Find +static unsigned int i2c_std_mode; line in ../meta-clanton-bsp/recipes-kernel/linux/files/clanton.patch file and assign 1 to that variable (add = 1 before semicolon):

Another patch is to allow configurable file system image file name. So that I can have multiple file system images on one SD card, and switch between them easily using GRUB menu. The patch is attached to this blog (rootimage.patch). Copy it to ../meta-clanton-distro/recipes-core/initrdscripts/files/ directory and add SRC_URI += "file://rootimage.patch;patchdir=${WORKDIR}" line to ../meta-clanton-distro/recipes-core/initrdscripts/initramfs-live-boot_1.0.bbappend file:

Once this patch is applied you can use rootimage=<filename>.ext3 option in the kernel command line in grub.conf to specify the root file system image file name. For example:

Reconfigure kernel, enable whatever features you like

Build the image

For information more information on available image profiles, see the "Images" chapter in the Yocto Project Reference Manual.

Install the image

Follow steps 9 - 11 above to install the image on the SD card.

Files and patches

For your convenience I attached a tarball which includes files with all the modifications described above and my kernel configuration with USB audio enabled. You can simply unpack it in to your build directory (one with meta-clanton_v0.7.5/ directory).