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Download and start the CoreOS development image in a container. Make sure to bind writable directories over the kernel's build and install paths.

wget 'http://alpha.release.core-os.net/amd64-usr/current/coreos_developer_container.bin.bz2'
bzcat coreos_developer_container.bin.bz2 > coreos_developer_container.bin
mkdir boot modules src
sudo systemd-nspawn \
    --bind="$PWD/boot:/boot" \
    --bind="$PWD/modules:/lib/modules" \

--bind="$PWD/src:/usr/src" \

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reg add "HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TimeZoneInformation" /v RealTimeIsUniversal /d 1 /t REG_DWORD /f

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If the CoreOS developer image was used to build custom kernel modules for the same kernel version as in a CoreOS image, these modules can be added to the existing set with overlayfs. This example mount unit illustrates this if the modules are available under /mnt. Note that usual overlayfs requirements apply: namely that the working directory must be on the same root as the upper layer, and it needs to support extended attributes.

[Unit]
Description=Add custom kernel modules into the mix

ConditionPathExists=/mnt/%v

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#!/bin/tail -n+2
menuentry 'CoreOS 1109.1.0' --class coreos --class gnu-linux --class gnu --class os --unrestricted {
	insmod part_gpt
	insmod fat
	set root='hd0,gpt7'
	linuxefi /coreos/vmlinuz-4.6.4-coreos kvm_intel.nested=1 coreos.autologin=tty1 coreos.configdrive=1
	initrdefi /coreos/coreos-1109.1.0.img
}

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[Unit]
Description=Start the local Fedora installation in a container
After=getty@tty2.service getty@tty3.service \
    boot.mount mnt-fedora.mount opt.mount
Conflicts=getty@tty2.service getty@tty3.service
Requires=mnt-fedora.mount
Wants=boot.mount opt.mount

[Service]
Delegate=yes

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#cloud-config
hostname: "set-this"

coreos:
  update:
    reboot-strategy: "off"

  units:
    - name: "default.target"
      command: "start"

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CoreOS Workstation Notes

This is a summary of the system setup used for the demonstration on 2016-07-18.

Goals / Requirements

This was put together with the following intent:

• It must build upon an unmodified CoreOS user space image.

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/* cc -o noodel -lseccomp noodel.c */
#include <seccomp.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int
main (int argc, char *argv[])
{
  scmp_filter_ctx ctx;

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#!/bin/bash -e

# Build a CentOS system with the configuration file from CoreOS.
config_url='https://raw.githubusercontent.com/coreos/coreos-overlay/master/app-emulation/wa-linux-agent/files/waagent.conf'
mirrorlist='http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os'
mirror=$(
         IFS=$'\n' urls=($(curl --location --silent "$mirrorlist"))
         echo "${urls[$((RANDOM % ${#urls[@]}))]}"
)

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{
  "ignition": { "version": "2.0.0" },
  "systemd": {
    "units": [
      {
        "name": "auto-update-kmods.service",
        "enable": true,
        "contents": "[Unit]\nDescription=Install custom kernel modules\nAfter=lib-modules.mount network-online.target\nRequires=lib-modules.mount network-online.target\nConditionPathExists=!/opt/modules/%v\nConditionPathExistsGlob=/lib/modules/auto-update-kmods.d/*.sh\n\n[Service]\nType=oneshot\nExecStart=/bin/bash -ex /lib/modules/auto-update-kmods.sh\n\n[Install]\nWantedBy=multi-user.target\n"
      },
      {