[Windows 8 General] antor44:
UEFI boot

I forgot I have a 10 inches version of this tablet, 32 GB, Windows 10 32 bits upgrade (first upgrade) and BIOS 2.0

UEFI multi-boot is not so difficult with: rEFInd, easyUEFI Windows application (because Windows changes boot order), linux's Unetbootin for USB boot, bootia32.efi archive for some linux's installations (Ubuntu-gnome 16.04.1 64 bits requires at least 7-10 GB and swap, may be 32 bits is a bit better because it's less RAM hunger), ... before tests, you have to disable Windows's Bitlocker encryption (AES-128 Windows disk software encryption for this model of the Atom processor, I think without hardware assistance, that it's seamless for the user because UEFI includes shared key, if disk key is deleted Microsoft online user account stores a large password), secure boot, fast boot, windows session identification (Microsoft online authentication sometimes locks session start, probably cause some autocheck of a efi boot manipulation... may be was "default_selection" option of rEFInd for booting last selected OS), backup efi boot partition (copy the files after mount partition)... then I gparted the Windows disk form USB (with no data loss).

And if someone can the microSD boot, Raspberry Pi community recommends Samsung EVO+ 32 GB, for about 10 $/€ (be warned about scam versions), with the best by far random IO, far less from 20 MB/s, but may be important for linux, although I don't know if max random IO of the card reader had been reduced too (most probably yes... and a lot).

Another chance is wubi EFI, a Ubuntu Windows installer that now supports UEFI 32 bits (the non approved by free-software community secure boot only with UEFI 64 bits), this install linux in a big file (resizable) of a NTFS Windows disk (again microSD doesn't boot, it requires a rEFInd's Card Reader firmware and is not available) and linux runs in loop mode inside this file. I installed Ubuntu-gnome 64 bits and 32 bits (in this case the installer requires a command-line option). UEFI32 too requires EasyUEFI and secure boot and bitlocker disabled, I utilized a USB wifi stick (TL-WN722N) until internal wifi was configured... I found lots of issues, including slow internal-wifi, soundcard, battery status, processor stepping and hangs, and other users's solutions for different tablets have not always worked... then no usability research here. Anyway, wubi is not the best way to install linux, although it works and it's easy, and Windows complain less.

A last possibility for linux could be VirtualBox 32 bits, this supports microSD use and Atom processor includes hardware assistance supporting even linux 64 bits. Virtualize linux on this tablet is very slow and touchscreen is a pain.

After some time I returned the tablet to its original state with no data loss*, USB boot still there or the install in a fast (if well chosen) microUSB 3.0 stick or microSD-adapter... but no charger without the use of a less portable, and manipulation disconnections, cable adapter. I utilized a cheap "octopussy" cable from China (3 USB 2.0+ microUSB for charge... 3-4 $/€ or less), but this tablet is incompatible for simultaneous operation (USB OTG+charge), it don't charge while USB use and only I can do slow charge with a tricky: connect with charge mode, change to OTG mode and connect USB devices (warning: some Amazon's users report issues or damages in other tablets).

*bitlocker key changed with a new online password stored for recovery, and Toshiba recovery (Bios option) was broken, may be caused by gparted or some UEFI boot application or some of the installed OS, who knows... normal fixes solutions don't work, although windows own recovery partition worked. Toshiba utilizes a particular EFI directory and Windows doesn't repair it, I copied Toshiba BCD backed up file or, in case it doesn't work, BCD file from Windows recovery boot directory (may be a normal fixboot is required first).