Which Linux Kernel shall I use?

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micro1
Posts: 42
Joined: Sun Jun 08, 2014 11:55 am

Which Linux Kernel shall I use?

Wed Apr 04, 2018 10:05 am

Hello,

i have some questions

1. Is it better to use the Kernel from linux4sam?
2. Or is it also OK to use the original Kernel from www.kernel.org
3. How ist the workflow will changes from the original Kernel go to linux4sam or vice versa?

Best regards
blue_z
Location: USA
Posts: 1690
Joined: Thu Apr 19, 2007 10:15 pm

Re: Which Linux Kernel shall I use?

Wed Apr 04, 2018 10:46 pm

micro1 wrote:1. Is it better to use the Kernel from linux4sam?
Better than what?
What is your criteria to determine "better"?
Do you need a specific device driver (or .dts file) for your SoC or board (e.g. as in this thread that you started)?
Do you need a kernel feature that's only in the mainline release?

micro1 wrote:2. Or is it also OK to use the original Kernel from www.kernel.org
"Original" kernel?
The usual descriptor for the kernel tree at kernel.org is mainline, not "original".

You can use whatever github/archive site you consider appropriate.
Those two aren't even the only sites for Linux kernel source that support Atmel/Microchip SoCs.
You haven't even touched the topics of kernel versions and release archive/tarball versus git clone.

micro1 wrote:3. How ist the workflow will changes from the original Kernel go to linux4sam or vice versa?
Are you just downloading and building a kernel, or planning to develop and submit patches?

Regards
micro1
Posts: 42
Joined: Sun Jun 08, 2014 11:55 am

Re: Which Linux Kernel shall I use?

Thu Apr 05, 2018 9:01 pm

Hello blue_z,

thnak you for help

1.
I meant with better which kernel have the better lerformance regarding the Atmel SoCs.
Is the mainline kernel more reliable regarding Atmel SoCs or are the SoC drivers in linux4sam further developed
and it will take a while until the drivers from linux4sam will be merged in the mainline kernel.

2.
Of course I meant mainline. What I not realy understand why a github repro linux4sam is necesary.
Are SoC drivers the same? For example Acme System use the mainline kernel Microchip use only
the kernel sources from linux4sam. So my question which kernel sources are the better choice?
Or which sources are the better or newer regarding Atmel SoCs?

3.
I am just downloding the sources and building the kernel. Mybe I will make some own patches but only for my use.
blue_z
Location: USA
Posts: 1690
Joined: Thu Apr 19, 2007 10:15 pm

Re: Which Linux Kernel shall I use?

Fri Apr 06, 2018 2:16 am

micro1 wrote:1.
I meant with better which kernel have the better lerformance regarding the Atmel SoCs.
Is the mainline kernel more reliable regarding Atmel SoCs ...
Using buzzwords for criteria is not sufficient. You have not specified any metrics.
The kernel configuration, the kernel version, and toolchain would probably have more impact on "lerformance" [sic] than the location of the source code.
Reliablity can be a crapshoot if you happen to perform the git clone after a risky patch has been commited.

micro1 wrote: ... or are the SoC drivers in linux4sam further developed
and it will take a while until the drivers from linux4sam will be merged in the mainline kernel.
In general that could be true.

micro1 wrote:What I not realy understand why a github repro linux4sam is necesary.
Maybe you don't understand software development.
Microchip/Atmel needs a repository that they can control for development of their products without the delays and hassles of submitting patches to mainline.
There can also be more or alternate configurations (e.g. .dts files for boards with various displays) that mainline will never accept.

micro1 wrote:For example Acme System use the mainline kernel Microchip use only the kernel sources from linux4sam.
Acme Systems sells boards. Why point its potential customers and users to another site where boards are also promoted?

micro1 wrote: So my question which kernel sources are the better choice?
Or which sources are the better or newer regarding Atmel SoCs?
You still haven't articulated any sensible criteria to make a reasonable choice.
I have already asked you two salient questions (regarding possible requirements) that could assist in a choice, but you have ignored them.
Besides, whatever you decide for a source, there will be someone else who will choose to use the other repository for their reasons.

micro1 wrote:3.
I am just downloding the sources and building the kernel. Mybe I will make some own patches but only for my use.
For a build tool such as Buildroot, it's a simple matter of specifying the name/location of the github repository or tarball.

Regards
micro1
Posts: 42
Joined: Sun Jun 08, 2014 11:55 am

Re: Which Linux Kernel shall I use?

Fri Apr 06, 2018 7:00 pm

Hello blue_Z
blue_z wrote

Using buzzwords for criteria is not sufficient. You have not specified any metrics.
The kernel configuration, the kernel version, and toolchain would probably have more impact on "lerformance" [sic] than the location of the source code.
Reliablity can be a crapshoot if you happen to perform the git clone after a risky patch has been commited.
Sorry typo I meant Performance regarding for exmaple correct DMA implemantation regarding UART or SPI.

blue_z wrote

In general that could be true.
This answer one of my biggest questions. So the drivers for Atmel SoC are newer on linux4sam then on the mainline.
So it can happen that on the mainline kernel a specific SoC driver mybee have some Bugs which are alredy fixed in
linux4sam kernel

blue_z wrote

Maybe you don't understand software development.
I understand now.
blue_z wrote

You still haven't articulated any sensible criteria to make a reasonable choice.
I have already asked you two salient questions (regarding possible requirements) that could assist in a choice, but you have ignored them.
Besides, whatever you decide for a source, there will be someone else who will choose to use the other repository for their reasons.
Critera are
1. DMA Performance of CAN-Bus, SPI Transfer, UART
blue_z
Location: USA
Posts: 1690
Joined: Thu Apr 19, 2007 10:15 pm

Re: Which Linux Kernel shall I use?

Sat Apr 07, 2018 2:18 am

micro1 wrote:So the drivers for Atmel SoC are newer on linux4sam then on the mainline.
Without the context of kernel version, that is not absolutely true.
micro1 wrote:So it can happen that on the mainline kernel a specific SoC driver mybee have some Bugs which are alredy fixed in linux4sam kernel
It could go either way.
I wouldn't be surprised if there's more activity for some mature/shared peripherals (e.g. the macb and atmel_serial drivers) on mainline (and mailing lists) than Linux4SAM.

micro1 wrote:Critera are
1. DMA Performance of CAN-Bus, SPI Transfer, UART
Obviously you didn't comprehend my remark on [lp]erformance, and you're only responding to half the salient questions.


Unless you can come up with any reason not to, you might as well simply use the Linux4SAM repository.
There's always going to be another update to the source code.
You're going to drive yourself crazy if you always try to use the latest version and patch-level and commits.

Regards
micro1
Posts: 42
Joined: Sun Jun 08, 2014 11:55 am

Re: Which Linux Kernel shall I use?

Mon Apr 09, 2018 10:13 pm

Unless you can come up with any reason not to, you might as well simply use the Linux4SAM repository.
There's always going to be another update to the source code.
You're going to drive yourself crazy if you always try to use the latest version and patch-level and commits.
I did it so. Thanks for help

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