Installing Debian testing (Buster) on the Jumper EZbook S3 notepad.

We downloaded the netinst image debian-buster-DI-alpha3-amd64-netinst.iso from the Debian Installer Page and copied over an USB memory stick (using dd, destination the whole device).

1. Insert the USB key and power-on the notebook. Quickly press the ESC key to eneter the BIOS setup.
2. Into the Boot section, increased the Setup Prompt Timeout to 5 seconds and disabled the Quiet Boot (not strictly required, but useful).
3. Changed the boot priority: at the 1st position choosed the UEFI: Generic Flash Disk, at the 2nd position the Windows Boot Manager.
4. Exit BIOS setup, saving changes.

During the installation we had an USB-Ethernet dongle connected, because the WiFi is almost certainly non-working. The product we used is identified on the USB bus as 0bda:5401: USB3.0 Hub with gigabit Ethernet.

We had to install the following non-free packages, to obtain the required firmwares:

• firmware-realtek (for rtlwifi/rtl8723bu_nic.bin and rtl_bt/rtl8723b_fw.bin)
• firmware-misc-nonfree (for i915/bxt_dmc_ver1_07.bin)

Everything went flawlessy with the Debian Installer: during manual partitioning we removed the main Windows partition (about 240 Gb) and a 700 Mb Windows Recovery partition. We leaved the first two reserver partition and created swap and rootfs:

The EFI boot loader was copied into the first partition, you can see it mounted into /boot/efi/EFI/debian/grubx64.efi.

The integrated WiFi card is attached to the USB bus, it is identified by ID obda:b720.

The WiFi did not work with the stock installation. The scanning for available access points is indeed working, but associating fails. After the failed association, even the scanning stops working. We upgraded the kernel to linux-image-4.17.0-1-amd64 in the hope that this will fix the WiFi problem, but nope.

We downloaded the sources of a kernel module (developed by lwfinger) which expressly states the compatibility with that device obda:b720. This is the source code GitHub page.

apt-get install git build-essential
cd /usr/local/src
git clone https://github.com/lwfinger/rtl8723bu.git
cd rtl8723bu
# In Makefile: commented-out the line EXTRA_CFLAGS += -DCONFIG_CONCURRENT_MODE
make
make install

This will install a new kernel module into /lib/modules/4.17.0-1-amd64/kernel/drivers/net/wireless/8723bu.ko and execute depmod to update the kernel modules list.

The kernel module will not survive a kernel upgrade (it should be recompilerd and reinstalled), so we have deinstalled the pseudo package linux-image-amd64 and leaved only the specific linux-image-4.17.0-1-amd64, to avoid automatic upgrades. The kernel module should be compatible with DKMS (the Debian kernel modules auto-building system), but our first try failed, so we went with the manual mode.

To be safe, blacklist the original kernel module by writing into /etc/modprobe.d/blacklist.conf the line:

blacklist rtl8xxxu

After a reboot you should find (lsmod) the module 8723bu loaded, instead of rtl8xxxu. Scanning for WiFi netwroks and association should work.

The WiFi adapter does not resume after the stand-by! It seems there is the issue #91 into the lwfinger rtl8723bu module, but already fiexd? A manual workaround is:

rmmod 8723bu
modprobe 8723bu

An automatic workaround seems to be creating an executable file /lib/systemd/system-sleep/fix-wifi with:

#!/bin/sh
case $1/$2 in
    pre/*)
        ;;
    post/*)
        modprobe -r 8723bu
        modprobe 8723bu
        ;;
esac

Tried with success the command line version of the commands:

systemctl suspend
systemctl hibernate

The hibernate requires a swap partition equal or greather than the available RAM.

• How to prevent the notebook to go into stand-by mode, which make it unreachable from the network (e.g. ssh login).
• Bluetooth not working?
• Enter key misbehaving in less. Problem: e.g. man page, backslash to search, hit Enter does not work, it prints ESCOM string instad. Workaround: use Ctrl-M. Tips: xev says that Enter sends KP_Enter instead of Return, but changing keysym with xmodmap -e "keysym KP_Enter = Return" does not resolve. Use .lesskey to modifiy?