GPD Pocket

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This article provides instructions on getting Gentoo operational on the GPD Pocket.

The GPD Pocket is a 7" UMPC manufactured by Game Park Digital running an Intel Atom x7-Z8750 and 8 GB RAM. Lots of work has already been done on getting the kernel to work out of the box by Hans de Goede.


The GPD Pocket contains the following hardware, the kernel should be configured to include drivers for all these items:

Hardware Kernel Configuration Key
USB Keyboard USB Options Enabled (xHCI also)
MAX17047 Fuel Gauge BATTERY_MAX17042
BQ24190 Charger CHARGER_BQ24190
Intel Graphics CONFIG_DRM_I915

I recommend compiling all these as modules they can then be tested in the normal way. Be careful of the Keyboard support though!



Knowledge of configuring the kernel is required here although it is quite simple.

This is the most complex step but you can avoid the pain by downloading the pre-built kernel from A kernel can be compiled from gentoo-sources in portage, a working configuration can be found on Hans de Goede's github linux-sunxi config (I can confirm that gentoo-sources-4.16.0 works). Also, gentoo-sources-4.16.0 contains the GPD Pocket fan driver.

root #emerge =gentoo-sources-4.16.0

Copy the .config file from Hans de Goede's GitHub repository into the /usr/src/linux-4.16.0-gentoo/.config directory.

This change to the linux-sunxi .config file should help with a funny sound driver problem:

root #make menuconfig
root #make -j4
root #mkdir /usr/src/modules-4.16.0-gentoo
root #make INSTALL_MOD_STRIP=1 INSTALL_MOD_PATH=/usr/src/modules-4.16.0-gentoo modules_install

The new kernel is available under /usr/src/linux-4.16.0-gentoo/arch/x86_64/boot/bzImage and the new modules in /usr/src/modules-4.16.0-gentoo

Creating an EFI-capable bootable USB drive

This will make all the data on the USB Stick inaccessible.

Use fdisk to create a new GPT partition table on the USB Stick. It is important that the partition table is GPT for a UEFI enabled machine to detect the UEFI partition.

root #fdisk /dev/sdc
Command (m for help): g
Created a new GPT disklabel (GUID: C799490C-B64C-4DF0-8466-7EDAB65294B3).

Command (m for help): n
Partition number (1-128, default 1): 1
First sector (2048-60547342, default 2048): 4096
Last sector, +sectors or +size{K,M,G,T,P} (4096-60547342, default 60547342): +256M

Created a new partition 1 of type 'Linux filesystem' and of size 256 MiB.

Command (m for help): t
Selected partition 1
Partition type (type L to list all types): 1
Changed type of partition 'Linux filesystem' to 'EFI System'.

Command (m for help): n
Partition number (2-128, default 2): 2
First sector (528384-60547342, default 528384):
Last sector, +sectors or +size{K,M,G,T,P} (528384-60547342, default 60547342):

Created a new partition 2 of type 'Linux filesystem' and of size 28.6 GiB.

Command (m for help): w

An EFI System partition is just a FAT32 partition, to set up the partition you may need to install sys-fs/dosfstools:

root #emerge --ask sys-fs/dosfsutils
root #mkfs.vfat -F32 /dev/sdc1

Mount the drive and make the UEFI boot directories:

root #mount /dev/sdc1 /mnt/sdc1
root #mkdir -p /mnt/sdc1/EFI/BOOT

Create a Linux root file system on /dev/sdc2:

root #mkfs.ext2 /dev/sdc2

Download and extract a stage 3 onto /dev/sdc2 (alter the mirror and date to flavor):

root #mount /dev/sdc2 /mnt/sdc2
root #cd /mnt/sdc2
root #tar -xf stage3-amd64-nomultilib-YYYYMMDD.tar.bz2

Edit the etc/passwd and etc/shadow files so that you can login.

Installing a bootloader

SYSLINUX will be used to boot the kernel, if syslinux is not installed on the system, do it now:

root #emerge --ask sys-boot/syslinux

Copy the required binaries to the USB drive:

root #cp /usr/share/syslinux/efi64/syslinux.efi /mnt/sdc1/EFI/BOOT/bootx64.efi
root #cp /usr/share/syslinux/efi64/ldlinux.e64 /mnt/sdc1/EFI/BOOT/ldlinux.e64

Create the syslinux configuration file:

FILE /mnt/sdc1/EFI/BOOT/syslinux.cfg
DEFAULT gentoo

LABEL gentoo
    LINUX ../vmlinuz-4.16.0-gentoo
    APPEND root=/dev/ram0 fbcon=rotate:1
    INITRD ../initramfs-4.16.0-gentoo.cpio.gz

The kernel and the RAM disk will be created next

Kernel and Initial RAM Disk

Creating a custom initramfs is explained here to allow access to the GPD Pocket internal eMMC flash and access to the USB stick that the root fs is installed on some modules must be available in the initramfs:

root #find lib/ -type f

These files can be copied from the kernel modules directory when a kernel is compiled with the Hans de Goede (or Fedora) settings.

The newly created initramfs and kernel should be copied to the EFI partition:

root #cp /usr/src/linux-4.16.0-gentoo/arch/x86_64/boot/bzImage /mnt/sdc1/EFI/vmlinuz-4.16.0-gentoo
root #cp /usr/src/initramfs-4.16.0-gentoo.cpio.gz /mnt/sdc1/EFI

Booting to the USB drive

To boot to the USB drive insert the drive into the GPD Pocket's USB socket and press F7 when the GPD Pocket is starting up (that means hold down the Fn key and press 7 a few times when you power up).

You should be presented with a list of startup options, one of which should be the name of your USB drive, select that one and syslinux should start and then boot the kernel and execute the initramfs.

Creating a GPD Userspace

I recommend creating a Virtual Machine or a Docker Container using a stage3 tarball, the VM or Container will be where all the applications are compiled and then installed on the GPD Pocket using portage's binary package support.

Configure Package Build Host

To begin, create and configure a clean Gentoo VM / Docker Container with the same configuration that will be used on the GPD Pocket:

FILE /etc/portage/make.conf
CPU_FLAGS_X86="mmx mmxext sse sse2 sse3 ssse3 sse4_1 sse4_2 avx aes"

Alter the PORTDIR, DISTDIR and PKGDIR to taste, this configuration is for a Portage Tree in SquashFS configuration.

The configuration for the GPD Pocket would look something like this, also be aware that the files in /etc/portage/package.use and /etc/portage/package.accept_keywords on both machines (the VM and your GPD Pocket) should match.

FILE /etc/portage/make.conf
CPU_FLAGS_X86="mmx mmxext sse sse2 sse3 ssse3 sse4_1 sse4_2 avx aes"
Although not strictly necessary it is probably better that the portage tree is the same on the VM and GPD Pocket, using SquashFS makes this easy and SquashFS images are provided on Gentoo mirrors!

From Stage3 to boot

OpenSSL and OpenSSH when compiled with the bindist use flag will not support wpa_supplicant which is required for the GPD Pocket to connect to a WiFi network. Emerge these on your VM.

root #emerge --oneshot openssl openssh
root #emerge linux-firmware
root #emerge wpa_supplicant

The brcmfmac driver (which is required for WiFi, see earlier) will not work properly with linux-firmware-20181026. The driver cannot find the file brcm/brcmfmac4356-pcie.txt, this file can be obtained from Google (and probably Broadcom). Fix is documented in this bug and by joshskidmore in his GPD Pocket guide for Arch Linux.

root #mv brcmfmac4356-pcie.txt /lib/firmware/brcm/brcmfmac4356-pcie.txt

Of course it will be difficult to install these packages without a network connection so install them from a chroot environment.

Configuring the Goodix Capacitive TouchScreen

The GPD Pocket orientation is incorrect (it is obvious when the device is booting). For the frame buffer terminal the kernel command line argument above {{{1}}} but for Wayland and X11 udev must be configured through the rules. This works if the X server is using libinput but if not different configuration specific to xorg-X11 may be required.

FILE /etc/udev/rules.d/99-goodix-touch.rules
ACTION=="add|change", KERNEL=="event[0-9]*", ATTRS{name}=="Goodix Capacitive TouchScreen", ENV{LIBINPUT_CALIBRATION_MATRIX}="0 1 0 -1 0 1"

The character between add and change is a pipe (|).

Found here (it works)

Configuring the UEFI Boot Menu

This is probably a good reference.

Setting up the GPD Pocket Fan

Newer kernels have a module for fan control on the GPD Pocket but annoyingly when the GPD Pocket is connected to AC supply the module defaults to switching the fan on. To modify this behaviour the module can be reloaded, first unload the module:

gpdpocket ~ #modprobe -r gpd-pocket-fan

Then, reload the module:

gpdpocket ~ #modprobe gpd-pocket-fan speed_on_ac=0

Fan on and off levels can be altered in a similar way for the fan to turn on at 40 degrees:

gpdpocket ~ #modprobe gpd-pocket-fan temp_limits=40000,40001,40002

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