Building a kernel module for the awus1900 Wifi stick and the Gemini PDA

A few days ago I have been asked if it is possible to build a driver for the awus1900 Wifi stick for the Gemini PDA. To be honest, I did not know, so I gave it a try.

The awus1900 uses Realtek’s rtl8814au chipset. The Linux driver for this chipset is available at many locations around the net. Most ones, I have tried, have not been compilable against the Gemini’s kernel. The driver at https://github.com/aircrack-ng/rtl8812au has been compilable with some minor modifications against the kernel source used for the kernel in Modular Linux kernel for the Gemini PDA with lid close fix.

First of all some parameters in the Makefile had to be changed to match the Gemini:

  • CONFIG_PLATFORM_I386_PC = n (disable x86 build)
  • CONFIG_PLATFORM_ARM64_RPI = y (enable arm64 build)

Some more parameters have been enabled for features in the hope that these do not cause problems:

  • CONFIG_POWER_SAVING = y
  • CONFIG_USB_AUTOSUSPEND = y
  • CONFIG_80211W = y

With all these changes the build fails complaining about STATION_INFO_SIGNAL and many more being undeclared. The module’s source expects these defines to be present in the kernel source for kernels below version 4.0. Most probably the Gemini kernel tree is different than other 3.x trees. So the line 23

#if (CFG80211_API_LEVEL >= KERNEL_VERSION(4, 0, 0))

in os_dep/linux/ioctl_cfg80211.c has been replaced with

#ifndef STATION_INFO_SIGNAL

to get the module source build against the Gemini’s kernel. Afterwards it has been possible to cross compile the kernel module by running make:

make ARCH=arm64 KSRC=/path_to_lib_modules_dir/3.18.41+/build

After building the module it can be copied to /lib/modules/3.18.41+/extra/ (or any other proper directory) on the Gemini and used afterwards. For those who do not want to build the module themselves, the binary modules for the kernel shared in the article Modular Linux kernel for the Gemini PDA with lid close fix can be downloaded from here: rtl88XX.zip (7 downloads)

Regards
Jürgen

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Libreoffice update failure

Today, when updating the Debian OS on my Gemini PDA, the upgrade for libreoffice failed complaining about the file dialog.xlc being present in multiple packages. A similar issue already has occurred with the Gemini PDA half a year ago¹. It is quite probable, that the same problem occurs with other Debian based distributions, as well. But let us have a look into the details first.

The usual update process (apt-get update;apt-get upgrade) resulted in apt complaining about the file dialog.tlc being present in both packages, libreoffice-base and libreoffice-common and failed:

Unpacking libreoffice-base (1:5.2.7-1+deb9u5) over (1:5.2.7-1+deb9u4) ...
dpkg: error processing archive /tmp/apt-dpkg-install-Y89hUD/03-libreoffice-base_1%3a5.2.7-1+deb9u5_arm64.deb (--unpack):
 trying to overwrite '/usr/lib/libreoffice/share/basic/dialog.xlc', which is also in package libreoffice-common 1:5.2.7-1+deb9u4
...
Errors were encountered while processing:
 /tmp/apt-dpkg-install-Y89hUD/03-libreoffice-base_1%3a5.2.7-1+deb9u5_arm64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

Every subsequent attempt to upgrade the system fails. The system now is in broken state, that prevents upgrades. In example a second try to run apt upgrade only resulted in the hint to try apt –fix-broken install:

root@gemini:/home/gemini# apt upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
You might want to run 'apt --fix-broken install' to correct these.
The following packages have unmet dependencies:
 libreoffice-base : Depends: libreoffice-base-core (= 1:5.2.7-1+deb9u4) but 1:5.2.7-1+deb9u5 is installed
                    Depends: libreoffice-base-drivers (= 1:5.2.7-1+deb9u4) but 1:5.2.7-1+deb9u5 is installed
                    Depends: libreoffice-core (= 1:5.2.7-1+deb9u4) but 1:5.2.7-1+deb9u5 is installed
 libreoffice-core : Breaks: libreoffice-base (< 1:5.2.7-1+deb9u5) but 1:5.2.7-1+deb9u4 is installed
                    Recommends: libpaper-utils but it is not installed
E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution).

Unfortunately, running apt –fix-broken install did not solve the problem:

root@gemini:/home/gemini# apt --fix-broken install  
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Correcting dependencies... Done
...
The following packages will be upgraded:
  libreoffice-base
1 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
22 not fully installed or removed.
Need to get 0 B/1.344 kB of archives.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] 
(Reading database ... 125897 files and directories currently installed.)
Preparing to unpack .../libreoffice-base_1%3a5.2.7-1+deb9u5_arm64.deb ...
Unpacking libreoffice-base (1:5.2.7-1+deb9u5) over (1:5.2.7-1+deb9u4) ...
dpkg: error processing archive /var/cache/apt/archives/libreoffice-base_1%3a5.2.7-1+deb9u5_arm64.deb (--unpack):
 trying to overwrite '/usr/lib/libreoffice/share/basic/dialog.xlc', which is also in package libreoffice-common 1:5.2.7-1+deb9u5
E: Sub-process /usr/bin/dpkg returned an error code (1)<br>

Since the error indicates clearly, that dpkg fails to overwrite the file dialog.xlc, I tried the solution I have used to fix the issue with the libreoffice update half a year ago. So I “instructed” apt-get to overwrite the conflicting files:

apt get -o Dpkg::Options::=”–force-overwrite” -f install

This finally solved the issue and allowed the libreoffice upgrade to complete:

root@gemini:/home/gemini# apt-get -o Dpkg::Options::="--force-overwrite" -f install
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Correcting dependencies... Done
...
The following packages will be upgraded:
  libreoffice-base
1 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
21 not fully installed or removed.
Need to get 0 B/1.344 kB of archives.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] 
(Reading database ... 125897 files and directories currently installed.)
Preparing to unpack .../libreoffice-base_1%3a5.2.7-1+deb9u5_arm64.deb ...
Unpacking libreoffice-base (1:5.2.7-1+deb9u5) over (1:5.2.7-1+deb9u4) ...
dpkg: warning: overriding problem because --force enabled:
dpkg: warning: trying to overwrite '/usr/lib/libreoffice/share/basic/dialog.xlc', which is also in package libreoffice-common 1:5.2.7-1+deb9u5
dpkg: warning: overriding problem because --force enabled:
dpkg: warning: trying to overwrite '/usr/lib/libreoffice/share/basic/script.xlc', which is also in package libreoffice-common 1:5.2.7-1+deb9u5
Processing triggers for mime-support (3.60) ...
Processing triggers for desktop-file-utils (0.23-1) ...
Processing triggers for libc-bin (2.24-11+deb9u3) ...
Processing triggers for man-db (2.7.6.1-2) ...
Processing triggers for shared-mime-info (1.8-1+deb9u1) ...
Unknown media type in type 'all/all'
Unknown media type in type 'all/allfiles'
Setting up fonts-opensymbol (2:102.7+LibO5.2.7-1+deb9u5) ...
Setting up uno-libs3 (5.2.7-1+deb9u5) ...
Processing triggers for hicolor-icon-theme (0.15-1) ...
Setting up ure (5.2.7-1+deb9u5) ...
Processing triggers for fontconfig (2.11.0-6.7+b1) ...
Setting up libreoffice-style-galaxy (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-common (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-core (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-gtk2 (1:5.2.7-1+deb9u5) ...
Setting up python3-uno (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-base-drivers (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-draw (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-avmedia-backend-gstreamer (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-java-common (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-script-provider-python (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-impress (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-math (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-base-core (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-calc (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-writer (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-base (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-librelogo (1:5.2.7-1+deb9u5) ...
Setting up libreoffice-report-builder-bin (1:5.2.7-1+deb9u5) ...
Setting up libreoffice (1:5.2.7-1+deb9u5) ...
Processing triggers for libc-bin (2.24-11+deb9u3) ...

The referenced thread¹ on oesf.org, regarding the past libreoffice upgrade issue, indicates there are quite some more possibilities that might fix the problem, but this one seems to be the easiest. So if this solution does not work for you, you might want to try one of the other solutions being shown there.

The libreoffice upgrade issue seems to be a reoccurring problem, thus a long term solution should be to fix the debian packages for libreoffice to not inlcude the same file in multiple packages. For the time being, the solution presented here solves the problem and gets the system back into a operational and upgradeable state.

Jürgen

References:
1. oesf.org: apt-get upgrade broke libreoffice

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Modular Linux kernel for the Gemini PDA with lid close fix

Sometimes, well, quite often, maybe one out of twenty times when closing the lid, the Gemini PDA running Debian did not turn off the screen and go to sleep, because of keys being pressed by the closing screen before the keyboard gets turned off. When one recognized the Gemini getting hot in the pocket already a quarter to a half of the battery juice was lost.

Recently Adam Boardman has fixed this annoying issue within the Gemini’s Linux kernel. His fix disables the keyboard directly upon lid close, rather than waiting for screen blanking via userspace control. Within a few days after the fix I have not noticed the issue anymore. This fix is more than worth another kernel build. Again, I want to share my kernel build below:

The kernel configuration is unchanged (with respect to the previous article), but included for completeness: gemini-3.18.41+-config.gz (17 downloads)

For the build, again the updated kernel source the from https://github.com/gemian/gemini-linux-kernel-3.18 has been used.

Again the kernel modules for the iptables MIRROR target (will not be usable with the default iptables version on the Gemini) and frandom are included.

Those who do not want to go through the build themselves can download my prebuild kernel from here:

Kernel Image: linux_boot-gemini-3.18.41+.img (23 downloads)
Modules: modules_firmware-gemini-3.18.41+.tar.gz (18 downloads)
(the kernel modules in the previous article should still work, however, the new build is included for completeness)

Instructions for flashing the image can be found on: support.planetcom.co.uk. Make sure to use a proper scatter file, in example the one that has been used for the initial flashing. Using the Download only mode of the flash tool is sufficient. Uncheck all partitions but boot (or boot1 or boot2, depending on your boot order). For the boot partition respectively the boot1 or boot2 partition select the downloaded kernel image.

Alternatively you can flash the kernel using dd:

dd if=linux_boot-gemini-3.18.41+.img of=/dev/block/disk/by-partlabel/boot

If Linux is not your primary operating system on the Gemini use boot1 or boot2 instead, depending on your partition layout.

After flashing, copy the modules archive onto your Gemini and extract it in your root directory:

cd /
tar -xzf /path_to/modules_firmware-gemini-3.18.41+.tar.gz

After rebooting the device, it should go to sleep reliably after closing the lid.


Jürgen

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Modular Linux kernel for the Gemini PDA with FOTA5 fixes

Recently the fixes in Planet Computers over the air update found their way into the Gemini Linux kernel sources. Thus the Linux kernel binaries I have shared before are a bit outdated now. So I have decided to build another kernel from the newer kernel sources with the following configuration changes with respect to the previous version:

•Enabled CONFIG_TOUCHSCREEN_MTK_SSL_SSD20XX (touchscreen driver for newer Gemini revisions)
•Added aeon_ssd2092_fhd_dsi_solomon to CONFIG_CUSTOM_KERNEL_LCM (use the touchscreen driver)
•Enabled CONFIG_USER_NS (for lxc and snapd)
•Enabled CONFIG_OVERLAY_FS (for lxc and snapd)
•Enabled CONFIG_SQUASHFS (for lxc and snapd)
•Enabled CONFIG_SQUASHFS_XATTR (for lxc and snapd)
•Enabled CONFIG_SQUASHFS_ZLIB (for lxc and snapd)
•Enabled CONFIG_SQUASHFS_XZ (for lxc and snapd)
•Enabled CONFIG_SQUASHFS_LZO (for lxc and snapd)
•Enabled CONFIG_SQUASHFS_LZ4 (for lxc and snapd)
•Enabled CONFIG_CRYPTO_LZ4HC (for lxc and snapd)

The changes and dependencies result in this kernel configuration: gemini-3.18.41+-config.gz (75 downloads)

For the build, again the updated kernel source the from https://github.com/gemian/gemini-linux-kernel-3.18 has been used.

Again the kernel modules for the iptables MIRROR target (will not be usable with the default iptables version on the Gemini) and frandom have been added.

Those who do not want to go through the build themselves can download my prebuild kernel from here:

Kernel Image: modules_firmware-gemini-3.18.41+.tar.gz (94 downloads)
Modules: linux_boot-gemini-3.18.41+.img (76 downloads)

Instructions for flashing the image can be found on: support.planetcom.co.uk. Make sure to use a proper scatter file, in example the one that has been used for the initial flashing. Using the Download only mode of the flash tool is sufficient. Uncheck all partitions but boot (or boot1 or boot2, depending on your boot order). For the boot partition respectively the boot1 or boot2 partition select the downloaded kernel image.

Alternatively you can flash the kernel using dd:

dd if=linux_boot-gemini-3.18.41+.img of=/dev/block/disk/by-partlabel/boot

If Linux is not your primary operating system on the Gemini use boot1 or boot2 instead, depending on your partition layout.

After flashing, copy the modules archive onto your Gemini and extract it in your root directory:

cd /
tar -xzf /path_to/modules_firmware-gemini-3.18.41+.tar.gz

After rebooting the device, it should behave somewhat more stable than it did before.

Regards
Jürgen

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Another improved modular Linux kernel for the Gemini PDA

The time has come for another modular linux kernel for the Gemini PDA. The linux kernel binaries I have shared before were lacking proper USB pendrive support. Whenever a drive got connected it froze and the device begun behaving strange, in example it has been impossible to open applications afterwards. Furthermore, in the meanwhile the Geminis keyboard ghosting issue got fixed in the updated kernel sources. Thus I have decided to build another kernel with the following changes:

•Enabled modules for more USB devices
•Enabled FB_UDL and DRM_UDL (for displaylink devices)
•Disabled SCSI_MQ_DEFAULT (for getting USB pendrives working again)

The changes and dependencies result in this kernel configuration: gemini-3.18.41+-config.gz (156 downloads)

For the build, again the updated kernel source the from https://github.com/gemian/gemini-linux-kernel-3.18 has been used.

Again the kernel modules for the iptables MIRROR target (will not be usable with the default iptables version on the Gemini) and frandom have been added.

Those who do not want to go through the build themselves can download my prebuild kernel from here:

Kernel Image: modules_firmware-gemini-3.18.41+.tar.gz (189 downloads)
Modules: linux_boot-gemini-3.18.41+.img (180 downloads)

Instructions for flashing the image can be found on: support.planetcom.co.uk. Make sure to use a proper scatter file, in example the one that has been used for the initial flashing. Using the Download only mode of the flash tool is sufficient. Uncheck all partitions but linux_boot (or boot if you boot into linux as default). For the linux_boot respectively the boot partition select the downloaded kernel image. With newer scatter files the boot partition names have changed to boot, boot1 and boot2. Select the appropriate  one for your Gemini.

Alternatively you can flash the kernel using dd:

dd if=linux_boot-gemini-3.18.41+.img of=/dev/block/disk/by-partlabel/boot

If Linux is not your primary operating system on the Gemini use boot1 or boot2 instead, depending on your partition layout.

After flashing, copy the modules archive onto your Gemini and extract it in your root directory:

cd /
tar -xzf /path_to/modules_firmware-gemini-3.18.41+.tar.gz

After rebooting the device, USB pendrives and other SCSI like devices like HDDs and DVD drives/burners should work again when attached to the Geminis USB ports.

Regards
Jürgen

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Improved modular Linux kernel for the Gemini PDA

The linux kernel binary I have shared in the article Modular Linux kernel for the Gemini PDA turned out to lack some important features, like not supporting the ethernet port of the Planet Computers USB hub. Thus a second version of the kernel had to be built.

In addition to the original changes, the following changes to the kernel configuration have been performed:

•Enabled modules for more USB devices
•Disabled CONFIG_MTK_CPU_HOTPLUG_DEBUG_0 (for less pollution in dmesg)
•Disabled CONFIG_MTK_CPU_HOTPLUG_DEBUG_3 (for less pollution in dmesg)
•Enabled  CONFIG_RCU_FAST_NO_HZ (for improved energy efficiency)
•Enabled CONFIG_RCU_BOOST (for better performance)

Originally I intended to also disable CONFIG_MTK_CPU_HOTPLUG_DEBUG_2, but then the build fails with an error regarding a static struct declaration.

The changes result in this kernel configuration: gemini-3.18.41+-config.gz (188 downloads)

For the build, the updated kernel source the from https://github.com/gemian/gemini-linux-kernel-3.18 with the fix for the Bluetooth vulnerability cve-2017-1000251 has been used.

Again the kernel modules for the iptables MIRROR target (will not be usable with the default iptables version on the Gemini) and frandom have been added.

Those who do not want to go through the build themselves can download my prebuild kernel from here:

Kernel Image: linux_boot-gemini-3.18.41+.img (220 downloads)
Modules: modules_firmware-gemini-3.18.41+.tar.gz (228 downloads)

Downloads outdated, new version at: Another improved modular Linux kernel for the Gemini PDA

Instructions for flashing the image can be found on: support.planetcom.co.uk. Make sure to use the same scatter file that has been used for the initial flashing. Using the Download only mode of the flash tool is sufficient. Uncheck all partitions but linux_boot (or boot if you boot into linux as default). For the linux_boot respectively the boot partition select the downloaded kernel image. With newer scatter files the boot partition names have changed to boot, boot1 and boot2. Select the appropiate  one for your Gemini.

Alternatively you can flash the kernel using dd:

dd if=linux_boot-gemini-3.18.41+.img of=/dev/block/disk/by-partlabel/boot

If Linux is not your primary operating system on the Gemini use boot1 or boot2 instead, depending on your partition layout.

After flashing, copy the modules archive onto your Gemini and extract it in your root directory:

cd /
tar -xzf /path_to/modules_firmware-gemini-3.18.41+.tar.gz

After rebooting the device some more USB peripherals, including the ethernet port of the Planet Computers hub, should work.

Regards
Jürgen

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Micro SD card performance with the Gemini PDA

Recently, when writing the article Some first tests with the Gemini PDA, I have noticed the ridiculous slow micro SD card I/O performance with Android. Because of this, later on, I did some further testing with Debian installed on the Gemini. After booting the device, the micro SD card read speed looks good, but after having the device suspended (i.e. closing the lid) the speed drops to about 20 MB/sec, which is consistent with the result of the Android test. So most  probably this also has been after a suspend. To pinpoint the problem a bit more, a more extensive test setup has been carried out.

Test setup

For this performance test the common tool hdparm has been used. On Debian based systems it can be installed from a root shell:

root@gemini:/home/gemini# apt-get install hdparm

Its usage for the test is quite simple:

root@gemini:/home/gemini# hdparm -t /dev/mmcblk1 

/dev/mmcblk1:
 Timing buffered disk reads:  62 MB in  3.05 seconds =  20.34 MB/sec

To make sure that the problem is not limited to the SD card that has been tried out initially, the test has been carried out with four different cards:

•SanDisk Ultra 200GB microSDXC Speicherkarte, Class 10, U1, A1
•Samsung EVO Plus Micro SDXC 128GB, Class 10, U3
•Samsung EVO MicroSDHC 64GB, UHS-I, Grade 1, Class 10
•SanDisk Ultra microSDXC 64GB, UHS-I, Class 10

The four tested cards are being shown in the photo below.

Tested Micro SD cards

Micro SD cards tested with the Gemini, from the left Sandisk Ultra 200GB, Samsung EVO Plus 128GB, Samsung EVO 64GB, Sandisk Ultra 64GB

For each card the read speed has been measured directly after startup and after closing the lid and reopening it. To ensure not to use fake or broken SD cards, all the cards also have been tested using a laptop with Gentoo Linux and a USB 3 card reader (Transcend TS-RDF8K). These speeds then can be compared to the results with the Gemini.

Results

The following table shows the results of the test as well as the “official” speed rating of the cards.

 SanDisk Ultra 200GBSamsung EVO Plus 128GBSamsung EVO 64GBSanDisk Ultra 64GB
after boot58.5 MB/s39.0 MB/s34.3 MB/s30.4 MB/s
after resume19.8 MB/s13.1 MB/s19.3 MB/s19.2 MB/s
with PC84.4 MB/s68.3 MB/s44.7 MB/s35.8 MB/s
rated speed100 MB/s100 MB/s48 MB/s30 MB/s

The measured speed of the two older 64GB cards is quite close to the rated speed, but the performance of the two 100MB/sec rated cards is far too low. Especially the results for the 128GB Samsung EVO are catastrophic. With the Gemini these cards operate at 57% respectively 69% of the speed  measured with the laptop. After suspending the Gemini the read speed of all cards drops below 20 MB/sec. The initial higher speed can only be achieved by rebooting the device. The results with the cards inserted into an external card reader attached to a laptop show that the cards generally are in a good working condition.

Conclusion

The test shows, that there is a performance issue with the Gemini PDA and micro SD cards. The higher rated cards operate far below their capabilities. For all the cards, the speed drops below 20 MB/sec after a suspend cycle. Thus, most probably there is a bug inside the Mediatek driver for the SD card reader, that prevents the cards from operating at high speed after a suspend cycle.  Also it might be possible to optimize the driver for newer cards. Hopefully these issues get resolved when the Gemini gets Android Oreo and a 4.X Linux kernel with it.

Jürgen

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