[Letux-kernel] Letux OS: Kernel 4.19-rc4

H. Nikolaus Schaller hns at goldelico.com
Wed Sep 19 11:03:00 CEST 2018


> Am 18.09.2018 um 19:04 schrieb N. Jackson <nljlistbox2 at gmail.com>:
> At 08:30 +0200 on Tuesday 2018-09-18, H. Nikolaus Schaller wrote:
>> So all this needs help and support from our community.
> For those who might help, it might be useful to have a primer on
> getting started. For me there are two questions:

Yes, I am happy to answer all such questions (knowledge sharing/transfer
is always good).

> Q1: Please can you clarify (perhaps, if appropriate, on one or more of
> the following web sites (rather than have the answer buried here in
> the list)) where the source code for the Pyra lives.
> I am confused between the following sites:
>  http://download.goldelico.com/letux-kernel/

this is an archive of precompiled binaries and links into the git repo
It is useful to temporarily install older kernels for comparisons.

And it is the repository where the makesd script looks for binary kernels
when baking an SD card.

The PyraOS has a different approach and repository. There, kernel tree
snapshots are taken and compiled with a root file system into complete
Debian SD images for installation by dd.

>  http://projects.goldelico.com/p/gta04-kernel/

this is the Letux Kernel project description where development takes place
it provides some resources, e.g. a how-to and links to the source code:


But beware, this project is not only for Pyra and has a lot of information
for other devices that are supported. It exists because the general problems
of other devices are almost the same and they sometimes share solutions
(e.g. some device drivers).

>  https://dev.pyra-handheld.com (requires an account?)

I don't use this resource. I think it is for user-space PyraOS, but someone
else should comment on this.

So some source of confusion is that low level development (U-Boot, Kernel)
is part of the LetuxOS project but what the user sees (PyraOS) is a
separate project that cherry-picks some parts of LetuxOS.

This is also the reason why two mailing lists exits.

> At 08:30 +0200 on Tuesday 2018-09-18, H. Nikolaus Schaller wrote:
>> Regarding 4.19-rc4 we have quite some construction sites, unfortunately
>> with some regressions.
>> Here is the list of (significantly) broken things that I am aware of:
>> Pyra:
>> * OMAP5 TILER is no longer scanning through the frame buffer and appears to fetch from a fixed address
>> * "reboot" hangs if timer8 is in use
>> * bq2429x charger driver is far from being perfect (sometimes does not
>> detect USB unplug/replug and charging does not start)
>> * AESS does not load firmware and even without, audio is broken
>> * PVR/SGX integration is missing
>> * sd/eMMC switch driver is missing
> Q2: For each of the above, which code is likely suspect
> * Upstream Linux?

Sometimes the problem is upstream (or introduced by API changes
not properly matched in our patches), so you don't know before
anaylsing and finding the root cause.

> * Letux patches to upstream Linux?

Most of these features are not at all upstream, but it may be the
interaction with mainline code which is the problem. Sometimes
a new driver reveals a bug in mainline (which was not found because
some combination wasn't used by anybody else).

For example the TILER did work up to 4.18.x but is broken since
4.19-rc1. There was some manual rebase conflict resolution involved,
so it might be a bug introduced by that. Or it might be a new API

In most cases these functional areas are in separate patch sets
based on latest mainline release (e.g. 4.19-rc4).

Here are some:

> * Pyra-project-specific code or configuration files?

Rarely, but can't be excluded.

> * TI OMAP drivers with source code and a free licence?

We have merged all TI open source code (SGX, AESS) into the
Letux tree.



> * TI blobs?
> And if the TI code or blobs don't live in the main repository,
> where
> are they?

Well, in most cases finding answers to these questions is part
of the task to be done :)

The SGX blobs are also known. And for AESS Marek has tried to rebuild
them but did not find time to succeed.


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