Patchy kernel? (or other software components)

[SneHebNor]

Hi,

sorry, if this is an FAQ:

1. How much is the kernel different from a stock Debian kernel package?
2. Are there any other packages patched or different from standard Debian?
3. Are additional packages needed for running the Pyra, that are not part of Debian?
4. If patches or additions are necessary, are there plans to get stuff into official Debian?

For various reasons*, I'm very much interested in running good old boring Debian as much as possible, even at the expense of performance.

Thanks in advance!

(*) Reasons:

1. I already trust Debian kernel and security teams to deliver security updates on all my machines. If they fail me, I'm in deep trouble anyway.
2. When there are any problems, I know that I can pester maintainers via bugs.debian.org - patched or additional packages are not under warranty, however.
3. Interferences between original Debian packages and specialised Pyra packages are less likely when there are few, ideally no, differences.

 

[TrashyMG]

How much is the kernel different from a stock Debian kernel package?

1. With ARM flavors of Debian, kernels are not packaged with the distribution. It's up to the vendor or end user to generate a working kernel. End user being the Pyra community.
2. See above...
3. most likely, the device tree setup is unique to the Pyra hardware. We will have our own debian repository... the sources will all be available if you feel any wrong doing is happening.
4. I doubt Debian would put in any Pyra hardware specific things. For the Kernel, we're mostly running on the Mainline Linux Kernel. I think the Ti guys/Nikolaus are checking in changes into the mainline once they confirm they're working.

 

[_jr_]

More kernel development info at http://projects.goldelico.com/p/gta04-kernel/

 

[stevenc99]

1. How much is the kernel different from a stock Debian kernel package?
2. Are there any other packages patched or different from standard Debian?
3. Are additional packages needed for running the Pyra, that are not part of Debian?
4. If patches or additions are necessary, are there plans to get stuff into official Debian?

Glad you asked! I've been looking over this the past couple of days:

1. as of letux-4.6-rc7: 462 files changed, 152858 insertions(+), 351 deletions(-) (between upstream 4.6-rc7 and http://git.goldelico.com/?p=gta04-kernel.git;a=shortlog;h=refs/heads/letux-4.6-rc7)
but that patchset adds support for many other devices than the Pyra (like, Pandora and GTA04) and test programs that don't belong upstream
yes - the basis kernel for the Pyra is only a week old! so the patches are being kept nicely up-to-date
the Linux 4.6 release even merged a couple of patches written by Nikolaus for the Pyra's SoC, so really the upstreaming has already started

2. I will take a closer look at http://packages.pyra-handheld.com/rootfs/ when I can get it running on some armhf board; almost all packages seem to be from the Debian jessie archive and unpatched; there were some additions/edits to configuration in /etc; overall a very clean image, professionally built

3. currently <10 Pyra-specific packages from a separate repository

4. I don't think any Debian packages were patched, so this is not necessary yet, except the kernel of course where hopefully more things can go directly upstream

the letux kernel is not built as a Debian package, but that would be nice... and even better if the grsecurity patch can be applied on top

1. With ARM flavors of Debian, kernels are not packaged with the distribution. It's up to the vendor or end user to generate a working kernel.

Debian's armhf-armmp (multi-processor) kernels support many boards, so it is possible...

https://wiki.debian.org/DebianKernel/ARMMP

 

[TrashyMG]

Debian's armhf kernel variant armmp supports many boards, so it is possible...[

Honestly this is the first I seen this... I've always had to shove a custom kernel into a raw rootfs in the past on every device I've had to deal with. It still looks like it has a limited amount of supported SoCs, I guess it's may just require selling the idea to the Debian group.

EDIT: cleaned up what I meant to say...

 

[stevenc99]

I know several Debian maintainers have pre-ordered a Pyra...

I'm sure the Pyra's Device Tree could be shipped in the Debian armmp packages, but patches for anything else really need to go upstream. The letux kernel patches add some totally new drivers for touchscreen, audio, etc.

 

[levi]

1. With ARM flavors of Debian, kernels are not packaged with the distribution. It's up to the vendor or end user to generate a working kernel. End user being the Pyra community.

Interesting. So ARM Debian isn't even a Linux till you add a kernel?

 

[Neelix]

Instant distro, just add kernel!

-Neelix

 

[Letalis Sonus]

So ARM Debian isn't even a Linux till you add a kernel?

Last time I checked they do offer a small selection of pre-made kernels for certain SoCs/boards.

 

[SneHebNor]

Glad you asked! I've been looking over this the past couple of days:

Many thanks for your elaborate answer! This looks not too bad for the world of ARM. Let's hope, that at least the divergence will decrease, not increase.

I have the gut feeling, that Pyra might become very popular in the Debian community! Let's see how many Pyras we will see in future DebConfs (Debian conferences). I say: Many!

 

[valhalla]

Honestly this is the first I seen this... I've always had to shove a custom kernel into a raw rootfs in the past on every device I've had to deal with. It still looks like it has a limited amount of supported SoCs, I guess it's may just require selling the idea to the Debian group.

EDIT: cleaned up what I meant to say...

For a device to be supported that way in Debian it must work with the mainline kernel, they don't accept patches to maintain.

If, however, support¹ for a certain board is in mainline kernel, debian is usually happy to distribute board specific files, including custom installer images; e.g. see the images linked to in section 5.1.5 at the end of https://d-i.debian.org/manual/en.armhf/ch05s01.html

Usually those images run the installer on the serial console, however, as that is the common denominator of all supported boards: I don't know how likely it would be to have an installer that is able to run on the pyra without requiring any extra computer, but it would be really cool.

¹ it doesn't have to be complete support for every feature of a SoC: e.g. a number of Allwinner based boards are supported in Debian even if up to jessie there is no support for audio and video out requires a newer uboot than the one in stable.

 

[stevenc99]

Perhaps a few Debian Developers could be bribed with a gift of a free Pyra Ideally in time for DebConf16!

BTW the latest u-boot package in experimental, and debian-installer in stretch, have just added support for the (yet unreleased) BeagleBoard-X15, which is not unlike the OMAP5 SoC that will be in the Pyra.