[Tinkerphones] GTA04A5 and News from the Kernel

H. Nikolaus Schaller hns at goldelico.com
Fri Oct 28 08:39:40 CEST 2016

Hi Jonas,

> Am 28.10.2016 um 01:56 schrieb Jonas Smedegaard <jonas at jones.dk>:
> [whoops, sorry for hitting send to early a moment ago]
> Quoting Paul Boddie (2016-10-27 22:24:20)
>> Cutting the GTA04 list because it isn't directly relevant, although I'm not
>> really sure of the relevance here anyway...
>> On Thursday 27. October 2016 19.43.27 H. Nikolaus Schaller wrote:
>>> Now back to the topic of FLOSS. This driver is of course free. But
>>> it will need / load firmware binaries into the GPU part of the SoC.
>>> These binaries are on one hand some "microkernel" running on the SGX
>>> GPU and the ARM libraries for OpenGL etc.
> [...]
>> Given what was said about the Broadcom SoC used in the Raspberry Pi,
>> the claims of "fully free" drivers and yet the continued presence of a
>> non-free microkernel, I can easily imagine the SGX functionality being
>> rather similarly structured, regardless of the larger SoC being
>> ARM-based (like the DM3730) or MIPS-based (like the JZ4780).
> As I understand it, there are 3 camps:
> a) refuse any non-free code, even difficult to replace soldered-on.
> b) refuse non-free runtime-loaded code executed anywhere.
> c) tolerate non-free code not affecting main CPU or its memory.
> d) Tolerate non-free code.
> I believe FSF is in the b) camp,and Debian is in the c) camp (and
> Debian+non-free is in d) camp).
> Problem with Raspberry Pi is not (only) that its GPU requires non-free
> code, but that its boot sequence is tied to the GPU so that it is not
> possible to even _boot_ without loading that non-free blob for the GPU.
> If I understand you correctly, Nikolaus, then the situation for this
> board is that it fits even FSF requirements (the phone works but slower
> without GPU, I guess),

Exactly. We have Replicant running on the GTA04 without GPU. The CPU is
sufficiently fast enough for doing standard wipe gestures and scrolling
through lists etc.

It is just that games (Pokemon...) and other applications that assume
presence of a fast OpenGL subsystem do not work. Or if I am informed
correctly it is very slow by using a CPU based OpenGL renderer. But others
know that better than me.

> and those wanting GPU can simply enable the
> non-free packages


> provided unofficially from Debian (which is the main
> grudge FSF holds against Debian).
> That is far better that the situation for Raspberry Pi which cannot be
> approved by FSF nor Debian - only works with Debian+non-free.

Exactly. The GTA04 works very well with free software only. What is not
working is WiFi and the GPU.

There is always some discussion into which category the firmware built
into some modules (the 3G module or GPS or even the Boot ROM of the
DM3730 SoC) falls.

All three are not open source so they are not available for code inspection
(without disassembly). But we have no means (tools) to change them. So
we can't install patched versions anyways.

This all is somewhere between a) and b) and did lead to discussions with
FSF and RMS some years ago but if I remember correctly RMS point of view
was: "if it can't be changed by installed software it can be considered
hardware". "Hard" in the sense of "unchangeable".

It would even be acceptable if some firmware blob from Debian non-free
would stored in some ROM during production and injected into the
WiFi chip autonomously by some hardware (additional microcontroller) [1].
As long as there is no connection from the SoC to modify this firmware
RMS would have been fine with it.

We rejected this approach because it is technically very complex and
we do not have the resources (time&money) to develop it. It would have
been something for a master student project...


[1]: http://projects.goldelico.com/p/gta04-main/issues/310/
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