README

   1 Crux-arm RaspberryPi2 Linux Kernel
   2
   3 NOTE: This README is wip. Some instructions are either vague or missing.
   4
   5 upstream sources:
   6   https://www.kernel.org/pub/linux/kernel/v4.x
   7   git://git.kernel.org/pub/scm/linux/kernel/git/statble/linux-stable.git
   8   https://github.com/raspberrypi/linux
   9
  10 Type make or make all to build kernel image, the device tree files/overlays,
  11 modules and related files. You may also find some of the other targets useful;
  12 either for rebuilding only a certain target or possibly downloading files for
  13 later offline build. These currently include:
  14
  15 all:        build all targets
  16 clean:      clean out built files/directories
  17 distclean:  clean, plus remove even downloaded files also
  18 files:      download all remote files
  19 config:     unpatch the kernel and copy the default config into the kernel tree
  20 image:      build zImage and rpi2 prep'd kernel image files
  21 dtb:        build device tree database/overlay files, tarball
  22 modules:    build kernel modules, tarball
  23 menuconfig: run menuconfig for kernel, starting with default kernel config
  24
  25 For booting the kernel, you will also need to download these addition files:
  26 bootcode.bin: https://github.com/raspberrypi/firmware/raw/master/boot/bootcode.bin
  27 start.elf: https://github.com/raspberrypi/firmware/raw/master/boot/start.elf
  28 fixup.dat: https://github.com/raspberrypi/firmware/raw/master/boot/start.elf
  29
  30 (Two other files are needed in the boot partition: config.txt and cmdline.txt.
  31  I will add more about these files next edit, as well as provide links to
  32  existing official/semi-official documentation for this files)
  33
  34 my current config.txt:
  35 disable_splash=1
  36 gpu_mem=256
  37 kernel=kernel7-4.5.4.img
  38 avoid_warnings=2
  39 dtoverlay=vc4-kms-v3d
  40
  41 my current cmdline.txt:
  42 dwg_otg.lpm_enable=0 console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty root=/dev/mmcblk0p3 rootfstype=ext4 rootwait
  43
  44 For the above two files, bare in mind that my sd card partition layout is as follows:
  45 mmcblk0p1: fat32, boot files (mounted to /boot in fstab)
  46 mmcblk0p2: swap
  47 mmcblk0p3: ext4, root filesystem
  48
  49 Sd card layout (as found on most howtos in the wild):
  50
  51 first partition, boot (fat32):
  52 kernel-$version.img, System.map-$version, bootcode.bin, start.elf, config.txt, cmdline.txt
  53 Untar the dtb tarball (dtb-$version.tar.*) to the boot partition.
  54
  55 second partition, root (ext{2,3,4}, xfs, btrfs, etc):
  56 Untar the modules tarball (modules-$version.tar.*) to the root partition.
  57 Untar all the package files created by crossrootfs and raspberrypi2-arm to
  58 the root partition.
  59
  60 Generating the kernel patch:
  61
  62 This is a stripped down description of how I generated the kernel patch.
  63 It is based on how I thought it might have been done by Alpine Linux for
  64 there raspberrypi kernel.
  65
  66 git clone -b rpi-4.5.y https://github.com/raspberrypi/linux.git linux-rpi
  67 cd linux-rpi
  68 git remote add -b linux-4.5.y stable-4.5 \
  69         git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
  70 git pull stable-4.5
  71 git diff linux-4.5.y..rpi-4.5.y > ../linux-4.5.y-rpi-$(date +%Y%m%d).patch