Installation on microsd

[Paul Mansfield]

Hi Marek and everybody,
glad to see some life in this!

the MMC slot is indeed problematic and you need the kernel parameter
     sdhci.debug_quirks=0x10000
or at least you used to, perhaps the TCM has a controller variant
which  is now better understood by modern kernels?

The biggest problem is that the UEFI firmware doesn't allow booting
from the microSD slot in the tablet. Well, at least I never got it to
work.

When I first started with the TCM, I didn't want to break the Windows
install, so I ran linux entirely off the microSD card in an adaptor
and put it in the dock. You have to use a GPT partition, and set the
EFI partition type correctly. In there went grub-efi etc. Then I had a
regular /boot, and a / partition. When the TCM powers on you can get
up a boot menu and boot off the card slot in the dock.

I used easyuefi in windows to set things up. And rEFInd really helps.

I found my TCM was very unstable, and the problem seemed to be the
kernel shutting down the USB hub or something. The SDIO wifi also a
contributor, if I used a USB wifi or ether device, it was much better.

What I then did was to shrink the Windows install in the eMMC, and put
a /boot partition in the eMMC, which can then be found by UEFI, and
linux then ran off the microSD card.

It was still unstable, so I shrank Windows more, and put linux
entirely into the eMMC. This really helped. However, the thing that
made it useable was limiting cstates.

My gut feel, backed up by work-rounds posted to the linux kernel
bugzilla, is that the storage hub in the Z3735F chip  which does SDIO
and eMMC has a design flaw, and in the event of any cstate switches,
has to be programmed very carefully to prevent the entire CPU locking
up.

Meanwhile, newer kernels have helped enormously.

It is possible to have a device which can use the sdio wifi,
accelerated video, and working sound now!