View source for Funtoo Linux Installation on Chromebook Pixel 2015

== '''Introduction''' ==

This article is a collection of thoughts, knowledge and procedures discovered while installing Funtoo linux on the Google Chromebook Pixel 2015. It is aimed to provide a concise explanation as well as a walkthrough of the components and steps required. However it will not go into the details of the applications or technologies, leaving that to external documentation.

{{note|This is an ongoing effort, e.g '''Under Construction'''}}

{{note|''While installing this machine I first wanted to just wipe everything and install Funtoo, but decided to dual boot at first to see how it behaves, identify possible optimizations etc., before wiping the rest of the ChromeOS installation. That being said, it might be worth noting that I did remove the firmware protection and set the flags as described in [[#Setting seaBIOS as default boot option]] before setting out on actually installing anything. So verification of certain parts of this article is required.''}}

{{important|Do anything described here or in the linked articles at your own risk, you may damage or otherwise make your device unusable and might need to contact Google for support. Be sure to read this article and all linked articles carefully, and '''only proceed to do something when you are sure you know what it does'''.}}

=== Developer Mode ===

Putting the Chromebook in [https://www.chromium.org/chromium-os/poking-around-your-chrome-os-device#TOC-Putting-your-Chrome-OS-Device-into-Developer-Mode developer mode] is a '''requirement'''. Also get accustomed to [https://www.chromium.org/chromium-os/poking-around-your-chrome-os-device#TOC-Getting-to-a-command-prompt opening the shell] and gaining root privileges. Note that changes to ChromeOS's root filesystem are not required for this, so '''no need to [https://www.chromium.org/chromium-os/poking-around-your-chrome-os-device#TOC-Making-changes-to-the-filesystem disable root filesystem verification]'''.

=== Crouton ===

It was suggested that [https://github.com/dnschneid/crouton crouton] is a viable alternative to installing a separate Linux distribution. The advantage is that it's simple and requires no partitioning. The downside are that your are limited in distribution choice.

=== Dual Booting vs. Funtoo only ===

There are some differences in how to install the system for either dual booting with ChromeOS or removing it. Most notably, it is reported that if the "Signed boot verification" is enabled and ChromeOS is replaced with a different system, "...then your system might become corrupted on empty battery, resetting dev_boot_usb dev_boot_legacy to their default values, forcing you to recover Chrome OS..."[ [https://wiki.archlinux.org/index.php/Chrome_OS_devices#Installation Arch linux wiki] ]. 

To avoid this, you can either Dual Boot or [[#Setting seaBIOS as default boot option]] and install Funtoo only. Another way would be to extract the kernel from ChromeOS and use that.

{{note|''I already disabled "Signed boot verification", so someone needs to try this without touching the firmware to confirm that dual boot works with unsigned kernels.''}}

== '''Preparing for Installation''' ==

To prepare an additional or alternative operating system we will need to do some common setup, like enabling usb and legacy boot and preparing the installation media, but it is also ''' ''highly recommended to make a full [[#Backup]] of the system before beginning'' '''.

=== Enabling USB boot ===

To enable usb boot run the following on ChromeOS as root: {{console|body=
###i## crossystem dev_boot_usb=1 dev_boot_legacy=1}}

=== Preparing and  testing the installation media ===

Installation can occur from pretty much any linux live environment, however for this article we'll be using [http://sysresccd.org system rescue cd]. In order to make sure you can boot to the live environment, reboot your device and press ctrl+d at the white screen just before ChromeOS boots. You should now be greeted by the SeaBIOS boot system from where you can boot your live environment. Please note that you might  have to play with the resolution options, especially for early boot print messages. What works for me in that case is to set vga=340 as parameter. 

=== Backup ===

After booting a live environment like [http://sysresccd.org system rescue cd] and mounting a large enough USB key (stock machines require about 2.0GB)  you can take a full backup with:
{{console|body=###i## dd if=/dev/sda {{!}} gzip > /mnt/usb_key/chromebook_pixel_2015_dd_backup.gzip}}

=== Setting SeaBIOS as default boot option ===

{{important|This step is only required for removing ChromeOS and installing funtoo on the whole drive. The steps in this section are all done in ChromeOS not the installation medium environment.}}

{{warning|This may damage your system, do at your own risk. You have been warned. Follow the steps on [https://www.chromium.org/chromium-os/developer-information-for-chrome-os-devices/chromebook-pixel-2015#TOC-What-s-inside- Developer Information from Chromium] to remove the '''firmware write protection''']. After this is done, do '''not''' reassemble the Chromebook. Turn it around, put it on a non-conductive, clean, clutter free surface and follow the steps below.}}

The first thing we need to do is disable the software write protection. Open a root shell and run {{c|flashrom --wp-status}} which will output something similar to: {{console|body=
flashrom v0.9.4  : 1d2f41b : Nov 12 2015 16:39:03 UTC on Linux 3.14.0 (x86_64), built with libpci 3.1.10, GCC 4.9.x-google 20150123 (prerelease), little endian
WP: status: 0x0080
WP: status.srp0: 1
WP: status.srp1: 0
WP: write protect is enabled.
WP: write protect range: start=0x00000000, len=0x00000000}}
To disable it run {{c|flashrom --wp-disable}} and double check if the command was successful with {{c|flashrom --wp-status}}. 

Now it's time to set the GBB Flags, enter {{f|/usr/share/vboot/bin}}, from there run {{c|set_gbb_flags.sh -h}} which will produce an output similar to the following:
{{console|body=
###i## ./set_gbb_flags -h
Changes ChromeOS Firmware GBB Flags value.

  Usage: /usr/share/vboot/bin/set_gbb_flags.sh [option_flags] GBB_FLAGS_VALUE
  
  Defined flags (some values may be not supported by all systems):

  GBB_FLAG_DEV_SCREEN_SHORT_DELAY            0x00000001
  GBB_FLAG_LOAD_OPTION_ROMS                  0x00000002
  GBB_FLAG_ENABLE_ALTERNATE_OS               0x00000004
  GBB_FLAG_FORCE_DEV_SWITCH_ON               0x00000008
  GBB_FLAG_FORCE_DEV_BOOT_USB                0x00000010
  GBB_FLAG_DISABLE_FW_ROLLBACK_CHECK         0x00000020
  GBB_FLAG_ENTER_TRIGGERS_TONORM             0x00000040
  GBB_FLAG_FORCE_DEV_BOOT_LEGACY             0x00000080
  GBB_FLAG_FAFT_KEY_OVERIDE                  0x00000100
  GBB_FLAG_DISABLE_EC_SOFTWARE_SYNC          0x00000200
  GBB_FLAG_DEFAULT_DEV_BOOT_LEGACY           0x00000400
  GBB_FLAG_DISABLE_PD_SOFTWARE_SYNC          0x00000800
  GBB_FLAG_DISABLE_LID_SHUTDOWN              0x00001000
  GBB_FLAG_FORCE_DEV_BOOT_FASTBOOT_FULL_CAP  0x00002000
  GBB_FLAG_ENABLE_SERIAL                     0x00004000

  To get a developer-friendly device, try 0x11 (short_delay + boot_usb).
  For factory-related tests (always DEV), try 0x39.
  For early development (disable EC/PD software sync), try 0xa39.

flags:
  -d,--[no]debug:  Provide debug messages (default: false)
  -f,--file:  Path to firmware image. Default to system firmware. (default: '')
  --[no]check_wp:  Check write protection states first. (default: true)
  -h,--[no]help:  show this help (default: false)
}}

The options we are interested in are: {{console|body=
GBB_FLAG_DEV_SCREEN_SHORT_DELAY 0x00000001
GBB_FLAG_FORCE_DEV_SWITCH_ON 0x00000008
GBB_FLAG_FORCE_DEV_BOOT_LEGACY 0x00000080
GBB_FLAG_DEFAULT_DEV_BOOT_LEGACY 0x00000400
}}

These options will set your device to boot to SeaBIOS by default. If we put these together we get 489, so the command we need to run becomes {{c|./set_gbb_flags.sh 0x489}}. Note that ChromeOS is still available, but now the booting is reversed ( e.g. ctrl+d on the white screen is now ChromeOS).

Once this is complete, re-enable the write protection with {{c|flashrom --wp-enable}}. Check if it still turns on, boots to SeaBIOS by default and to ChromeOS via ctrl+d. Finally turn the device completely off {{c|shutdown -h now}}. Proceed to putting the write protection back into place and reassemble the device. 

== '''Preparing the hard drive''' ==

There are two distinct ways in which you can prepare the hard drive, either for dual booting purpouses or for installing Funtoo only. The later option should be easier, but will require you to [[#Setting SeaBIOS as default boot option]]. In both scenarios your data on the ChromeOS's State drive will be lost. This is the local data, not the one synced with Google's cloud system. Nonetheless it is recommended to make a backup of the files you hold dear at this point.

=== Preparing for Dual-Boot ===

Chrome OS has a distinct partition layout that it depends on. For more information on the specifics of the ChromeOS boot and partition layout visit the [https://www.chromium.org/chromium-os/chromiumos-design-docs/disk-format Chromium documentation]. Fortunately there is a partition that is unused for now (as described in the [https://www.chromium.org/chromium-os/chromiumos-design-docs/disk-format#TOC-Drive-partitions drive partition documentation on Chromium.org]). The KERN-C and ROOT-C partitions are "Minimal-size partition for future third kernel. There are rare cases where a third partition could help us avoid recovery mode (AU in progress + random corruption on boot partition + system crash). We decided it's not worth the space in V1, but that may change". The space for our new Funtoo installation will come from the STATE drive of ChromeOS (" User's browsing history, downloads, cache, etc. Encrypted per-user."), which means we'll shrink this partition and allocate the newly gained space to KERN-C and ROOT-C. While it will be explained how to do this manually,  you can use the [https://github.com/hawk416/chrome/blob/master/chromeShrinkState.sh chromeShrinkState] script to simplify this process. Simply put this script onto a USB key for now.

It is recommended to fully shutdown the chromebook and restart it at this point. Do '''not''' login to ChromeOS, press {{c|ctrl+alt+f2}} at the login prompt to be taken to VT2, and login as the "chronos" user and run {{c|sudo}} to gain root privileges. Turn off {{c|powerd}} to stop the display timing out, the {{c|ui}} and {{c|cryptohomed}} to stop processed from using the state partition:
{{console|body=###i## initctl stop ui}}
''Note that stopping the "ui" will log you out and you will have to log back in and gain root privileges.
{{console|body=###i## initctl stop  cryptohomed}}
{{console|body=###i## initctl stop powerd}}
Check where {{f|/dev/sda1}} is mounted with:
{{console|body=
###i## mount {{!}} grep /dev/sda1
/dev/sda1 on /mnt/stateful_partition type ext4 (rw,nosuid,nodev,noexec,relatime,commit=600,data=ordered)
/dev/sda1 on /home type ext4 (rw,nosuid,nodev,noexec,relatime,commit=600,data=ordered)
/dev/sda1 on /usr/local type ext4 (rw,nodev,relatime,commit=600,data=ordered)
}}
Check if anything is using these mounts and kill any processes using them:
{{console|body=###i## lsof {{!}} grep /home}}
{{console|body=###i## lsof {{!}} grep /home}}
{{console|body=###i## lsof {{!}} grep /usr/local}}

You can now proceed to run  {{c|chromeShrinkState}} from the USB drive. Make sure to boot into ChromeOS after the script finishes to rebuild it's state partition. The rest of this section will explain how this is done manually, so read on if you'd like to do it that way or know what the script is doing.

==== Manually repartitioning ====

First it is recommended to check if ROOT-C and KERN-C are size 1 {{c|cgpt show -i 6 -s /dev/sda}} and {{c|cgpt show -i 7 -s /dev/sda}}. Make sure this is the case as otherwise it means that there is something already on those partitions.

To repartition the state drive we'll need some info, specifically we'll need to know the current size and start of the state partition {{c|cgpt show -i 1 -s /dev/sda}} and {{c|cgpt show -i 1 -b /dev/sda}}. To help with the calculations we can assign variables to this values {{c|state_size{{=}}cgpt show -i 1 -s -q /dev/sda}} and {{c|state_start{{=}}cgpt -i 1 -b -q /dev/sda}} .

We need the size of the root filesystem in sectors, which are 512B in size. We can use the simple formula "N*1024*1024*2" where N is the number of GigaBytes or "N*1024*2" in the case of MegaBytes {{c|root_size{{=}}$((GB*1024*1024*2))}} . We will also do the same for kern_size: {{c|kern_size{{=}}$((MB*1024*2))}} which will host our boot partition. 
To calculate the new state size, we need to substract both root and kern size from the current state size: {{c|state_size_new{{=}}$(($state_size - $kern_size -$ root_size))}}. The last things we need are the new start sectors for kern and root, which can be found by adding the state_size to state_start for kern_start and later add kern_start and kern_size to form root_start: {{c|kern_start{{=}}$(($start_start + $state_size_new))}} and {{c|root_start{{=}}$(($kern_start + $kern_size))}}.

Now we can proceed to write the new partition table:
{{console|body=###i## cgpt add -i 1 -b $state_start -s $state_size_new -l STATE /dev/sda}}
{{console|body=###i## cgpt add -i 6 -b $kern_start -s $kern_size -l KERN-C -t "kernel" /dev/sda}}
{{console|body=###i## cgpt add -i 7 -b $root_start -s $root_size -l ROOT-C /dev/sda}}

Once finished you will need to reboot, make sure to boot into ChromeOS first for it to rebuild it's state partition before continuing.

=== Preparing for Funtoo only ===

Preparing for a single operating system, or even multiple linux systems is easy, as long as your willing to remove ChromeOS completely. Make sure to read [[#Setting SeaBIOS as default boot option]] and be sure you understand the risks of [https://www.chromium.org/chromium-os/developer-information-for-chrome-os-devices/chromebook-pixel-2015#TOC-Firmware-Write-Protect disabling the firmware write protection]. Once SeaBIOS is set as the default boot option you can boot into the live environment and partition the  drive as per the [http://www.funtoo.org/Install#Prepare_Hard_Disk Installation guide].

== '''Installation''' ==

The installation generally follows the [http://www.funtoo.org/Install Funtoo installation guide], however some of the steps need to be amended for the device to work properly.

=== Profile Settings ===
Once you have successfully booted into the system you should set up the [[Funtoo Profiles|Funtoo profile settings]] for consequent builds. First select the intel64-broadwell subarch profile using the ego tool. 

{{console|body=###i## ego profile subarch intel64-broadwell}}

Next, select appropriate mix-ins depending on required functionalities. Select '''X''' for running Xorg server and WM or Desktop environments. Another option is '''no-systemd''' for an OpenRC based init-system (default for Gentoo/Funtoo).

{{console|body=###i## ego profile mix-ins X no-systemd}}

You can list all available profile settings:

{{console|body=###i## ego profile list

=== flavor: ===

    core*, desktop, hardened, minimal, server, workstation

=== build: ===

    (current*), experimental, stable

=== arch: ===

    arm-32bit, pure64, x86-32bit, (x86-64bit*)

=== subarch: ===

    amd64-bulldozer, amd64-excavator, amd64-jaguar, amd64-k10
    amd64-k8, amd64-k8+sse3, amd64-piledriver, amd64-steamroller
    atom_64, btver1_64, core-avx-i, core2_64, corei7, generic_64
    intel64-broadwell*, intel64-haswell, intel64-ivybridge, intel64-nehalem
    intel64-sandybridge, intel64-silvermont, intel64-westmere
    native_64, nocona, opteron_64, xen-pentium4+sse3_64

=== mix-ins: ===

    X*, audio, cinnamon, console-extras, dvd, gnome, gnome-3.16-fixups
    hardened, kde, kde-plasma-5, lxde, lxqt, mate, media, media-pro
    mediadevice-audio-consumer, mediadevice-audio-pro, mediadevice-base
    mediadevice-video-consumer, mediadevice-video-pro, mediaformat-audio-common
    mediaformat-audio-extra, mediaformat-gfx-common, mediaformat-gfx-extra
    mediaformat-video-common, mediaformat-video-extra, no-emul-linux-x86
    no-systemd*, openvz-host, print, python3-only, vmware-guest
    xfce
}}

=== Kernel choice and Configuration ===

Although current Funtoo Linux stage3's include a prebuilt {{Package|sys-kernel/debian-sources}} kernel which should boot the Pixel fine, there may be issues with it as not all drivers for the pixel are available yet.
The other option is to use the linux-samus kernel from https://github.com/raphael/linux-samus. Clone the repository to your /usr/src/ folder. Create a link from the linux-samus kernel to /usr/src/linux: 
{{console|body=
$ ##i##cd /usr/src/linux
$ ##i##git clone https://github.com/raphael/linux-samus
$ ##i##ln -snf /usr/src/linux-samus /usr/src/linux
}}
Before building/configuring the kernel, you might want to branch the repository and then patch it with genpatches from: https://dev.gentoo.org/~mpagano/genpatches/ .  This will add the gentoo/funtoo required options in a top level category and select them.
{{console|body=
$ ##i##git branch linux-samus-<version>-genpatches
$ ##i##git checkout linux-samus-<version>-genpatches
$ ##i##mkdir genpatches
$ ##i##cd genpatches
$ ##i##wget https://dev.gentoo.org/~mpagano/genpatches/tarballs/genpatches-<version>.base.tar.xz
$ ##i##wget https://dev.gentoo.org/~mpagano/genpatches/tarballs/genpatches-<version>.extras.tar.xz
$ ##i##wget https://dev.gentoo.org/~mpagano/genpatches/tarballs/genpatches-<version>.experimental.tar.xz
$ ##i##for x in $(ls); do tar xf $x; done
$ ##i##cd ../linux/
$ ##i##for patch in $(find /usr/src/linux-samus/genpatches/ -iname *.patch | sort); do patch -p1 -i $patch; done
}}
After you have successfully patched the kernel sources, you can follow the typical kernel installation: 
{{console|body= 
$ ##i##cd linux-samus/build/linux
$ ##i##make nconfig
$ ##i##make -j4
$ ##i##sudo make modules_install
$ ##i##sudo make install
}}

Assuming GRUB is installed and MBR boot is working as per article [[Install/BootLoader|Funtoo Install Guide - Installing Bootloader]]
Once the kernel is built and copied to {{f|/boot}}, entry must be added to {{f|/etc/boot.conf}} eg:
{{console|body= 
###i##  printf "\"Funtoo linux-samus 4.4.2\" { \n  kernel vmlinuz-4.4.2ph \n }"  >> /etc/boot.conf
}}

{{note|If you wish to select this kernel as default option you can change default setting in {{f|/etc/boot.conf}} }}

Then run  {{c|boot-update}}
{{console|body= 
###i## boot-update
boot-update 1.7.3 /
Copyright 2009-2015 Funtoo Technologies

 [use option "-l" for license info, "-h" for help]

 * Generating config for grub...

           Funtoo Linux - Kernel-4.5.3-Chromebook_pixel_2015
           Funtoo 4.4.4 Linux - Kernel-4.4.4-Chromebook_pixel_2015
 ##b##DEFAULT >##!b## ##g## Funtoo linux-samus 4.4.2 - vmlinuz-4.4.2ph##!g##

 * NOTE : Detected MBR boot. Configuring for Legacy MBR booting.
 * Completed successfully.

}}

=== Graphics ===
In order to run X with hardware acceleration supported by the HD Graphics 5500 GPU first set ''VIDEO_CARDS'' in {{f|/etc/portage/make.conf}}.
{{file|name=/etc/portage/make.conf|desc=Add the following line |body=
VIDEO_CARDS="intel i965"
}}
When {{package|x11-base/xorg-server}} and {{package|x11-base/xorg-drivers}} are installed, the ''VIDEO_CARDS'' USE_EXPAND flag will ensure installation of correct drivers.
Additional ''USE flags'' for intel drivers can also be used.
{{file|name=/etc/portage/package.use/xf86-video-intel|desc=Use flags |body=
x11-drivers/xf86-video-intel dri3
}}
{{file|name=/etc/portage/package.use/xorg-server|desc=Use flags |body=
x11-base/xorg-server glamor
}}

=== Touchpad ===
Once you have booted in the [https://github.com/raphael/linux-samus linux-samus] kernel you should run the {{f|linux-samus/scripts/setup/touchpad/enable-atmel.sh}} script. 
{{console|body=
$ ##i## cd linux-samus/scripts/setup/touchpad
$ ##i## ./enable-atmel.sh
}}
This will setup the Atmel touchpad and touchscreen devices. Although {{Package|x11-base/xorg-server}} will use {{Package|x11-drivers/xf86-input-synaptics}} drivers for the touchpad, this configuration seems to work.
Config file {{f|/etc/X11/xorg.conf.d/25-touchpad.conf}} can be edited for preferred behavior.
{{file|name=/etc/X11/xorg.conf.d/25-touchpad.conf|desc=This is a sample config that enables some capabilities of the touchpad|body=
Section "InputClass"
    Identifier "touchpad"
    MatchIsTouchpad "on"
    MatchDevicePath "/dev/input/event*"
    Driver "synaptics"
        Option "TapButton1" "1"
        Option "TapButton2" "3"
        Option "TapButton3" "2"
        Option "VertEdgeScroll" "on"
        Option "VertTwoFingerScroll" "on"
        Option "HorizEdgeScroll" "on"
        Option "HorizTwoFingerScroll" "on"
        Option "CircularScrolling" "on"
        Option "CircScrollTrigger" "2"
        Option "EmulateTwoFingerMinZ" "40"
        Option "EmulateTwoFingerMinW" "8"
        Option "CoastingSpeed" "0"
        Option "FingerLow" "30"
        Option "FingerHigh" "50"
        Option "MaxTapTime" "175"
	Option "VertScrollDelta"          "-50"
        Option "HorizScrollDelta"         "-50"
EndSection
}}

You can refer to man pages to see all available options. 
{{console|body=$ ##i## man synaptics}}

{{note|If you wish to use xf86-input-cmt driver follow the steps below. You'll have to build it yourself with additional libraries ported from ChromeOS}}

{{important|If you wish to use ported drivers you should remove the default Synaptics package and its configuration file.}} 

There is a script {{f|touchpad-cmt.sh}} included in {{f|linux-samus/scripts/setup/touchpad/}}. It will attempt to download libraries {{c|libgestures}}, {{c|libdevc}} and {{c|xf86-input-cmt}} X11 ChromiumOS touchpad driver ported to Linux from [https://github.com/hugegreenbug/ Hugh Greenberg's repositories]. Requirement for {{c|libgestures}} is {{Package|dev-libs/jsoncpp}} so let's install that first:
{{console|body=
###i## emerge -a jsoncpp
}}

Then we run the setup script:
{{console|body=
# ##i## cd linux-samus/scripts/setup/touchpad
# ##i## ./touchpad-cmt.sh
}}

It will copy {{f|40-touchpad-cmt.conf}} and {{f|50-touchpad-cmt-samus.conf}} to {{f|/etc/X11/xorg.conf.d/}}. Both files contain relevant settings for this particular touchpad. Because this scripts removes working directories after it is done, you can find other configurations in the [https://github.com/hugegreenbug/xf86-input-cmt/tree/master/xorg-conf xf86-input-cmt repo].

{{file|name=/etc/X11/xorg.conf.d/50-touchpad-cmt-samus.conf|desc=Useful options |body=
Option          "Australian Scrolling" "1" # Enables inverse scrolling with two fingers
}}

=== Audio ===
In order to have fully functional audio on Pixel, [http://www.alsa-project.org/main/index.php/Main_Page ALSA] and {{Package|media-sound/pulseaudio}} are needed.
{{note|ALSA support must be enabled in kernel. [https://github.com/raphael/linux-samus Linux-samus] kernel config already has all the necessary options enabled.}}
Before necessary packages are emerged, we can set some useful global USE flags in {{f|/etc/portage/make.conf}}. Needed flags are {{c|alsa sound pulseaudio acpi}}.
Then emerge  {{Package|media-sound/pulseaudio}} along with three needed ALSA packages: {{Package|media-sound/alsa-utils}}, {{Package|media-plugins/alsa-plugins}}, {{Package|media-libs/alsa-lib}}.
{{console|body=
###i## emerge -a pulseaudio alsa-utils alsa-plugins alsa-lib
}}

For headphone/speaker automatic switching to work {{Package|sys-power/acpid}} is needed as well. If it is not yet installed this is a good time to run
{{console|body=
###i## emerge -a acpid
}}
and then
{{console|body=
###i## rc-update add acpid default
}}
to have the service start at boot time.
{{note|Pulseaudio also requires {{Package|sys-auth/consolekit}} for permission management. For more information about Pulseaudio please check the [https://wiki.gentoo.org/wiki/PulseAudio wiki].}}

Setup the rest of the configuration following https://github.com/raphael/linux-samus instructions under "Post-install steps".

=== Keyboard/Brightness/Xorg ===
Setup the rest of the configuration following https://github.com/raphael/linux-samus instructions under "Post-install steps".