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Kernel 4.19 - USB Gadget? Do I need to upgrade? How do Kernel versions work?

Posted: Wed Dec 04, 2019 6:05 am
by robear
Hi!

I am trying to make a usb gadget project following: http://www.isticktoit.net/?p=1383

I am starting with: 2019-09-26-raspbian-buster-lite
On initial install I get kernel: linux simknob 4.19.75+ #1270 Tue Sep 24 18:38:54 BST 2019 armv6l GNU/Linux
They say:
We need to use the 4.4 Kernel, which is currently (Feb. 2016) not installed on the default Raspbian image. But upgrading is easy: just run

Code: Select all

sudo BRANCH=next rpi-update
I am a bit confused about kernel versions. Searching around I see people talking about running 4.4.11, 4.59, etc., but I cannot find a 'hash' to install those versions with rpi-update. I also cannot find any concise information around using these kernel versions.

If I do a simple rpi-update, I get kernel 4.19.86+, which is apparently the current development kernel? Was there ever official 4.4 support? Does the isticktoit blog actually mean '4.19.4' ? or maybe 4.14 ?

Thanks in advance for any explanations!

Re: Kernel 4.19 - USB Gadget? Do I need to upgrade? How do Kernel versions work?

Posted: Wed Dec 04, 2019 6:06 pm
by hippy
4.19 is later than 4.4 so you shouldn't have to worry about the kernel you have. You would only need to upgrade if you had an earlier version, as may have been the case in 2016, but not now.

And best not to run rpi-update. Ever. Not unless directly instructed by an RPT engineer on this forum.

Re: Kernel 4.19 - USB Gadget? Do I need to upgrade? How do Kernel versions work?

Posted: Wed Dec 04, 2019 7:34 pm
by DougieLawson
Stop now!

BRANCH=next rpi-update will leave your system unbootable (with a kernel that's almost a year out of date - that won't boot on an RPI4). What possible reason do you have for wanting to run rpi-update? What's missing from 4.19.75 (current stable kernel)? What's not in the development and experimental 4.19.86 kernel?

Re: Kernel 4.19 - USB Gadget? Do I need to upgrade? How do Kernel versions work?

Posted: Fri Dec 06, 2019 5:15 pm
by robear
DougieLawson wrote:
Wed Dec 04, 2019 7:34 pm
Stop now!

BRANCH=next rpi-update will leave your system unbootable (with a kernel that's almost a year out of date - that won't boot on an RPI4). What possible reason do you have for wanting to run rpi-update? What's missing from 4.19.75 (current stable kernel)? What's not in the development and experimental 4.19.86 kernel?
My issue is not understanding the version numbering system it appears. The poster above mentions 4.19 is newer than 4.4. I am sure you understand this is not intuitive? I have attempted googling for specific information about this and could not find a list of kernel versions and release date, or some sort of way to relate the linux kernel number to these raspbian release numbers. Are they the same?

The poster above has really helped me a lot to understand the situation. I now know 4.19 is newer than 4.4. Now I still need to learn how I could have known that in the first place. All the information is disjointed and seems to assume you know the last kernel version(s) history.

Is there a changelog or other one-stop location for all the kernel updates?

Re: Kernel 4.19 - USB Gadget? Do I need to upgrade? How do Kernel versions work?

Posted: Fri Dec 06, 2019 5:33 pm
by hippy
robear wrote:
Fri Dec 06, 2019 5:15 pm
I now know 4.19 is newer than 4.4. Now I still need to learn how I could have known that in the first place.
Versions of anything normally increment; 19 is greater than 4 so must have come later, though I suppose it is natural, if one reads it as a whole and as a decimal, then 4.4 is larger than 4.19 which confuses things.

I never use single digit version numbers for this exact reason, would have had 4.04 and 4.19 or gone from 4.9 to 5.0 and carried on from there.

Re: Kernel 4.19 - USB Gadget? Do I need to upgrade? How do Kernel versions work?

Posted: Fri Dec 06, 2019 5:38 pm
by robear
hippy wrote:
Fri Dec 06, 2019 5:33 pm
robear wrote:
Fri Dec 06, 2019 5:15 pm
I now know 4.19 is newer than 4.4. Now I still need to learn how I could have known that in the first place.
Versions of anything normally increment; 19 is greater than 4 so must have come later, though I suppose it is natural, if one reads it as a whole and as a decimal, then 4.4 is larger than 4.19 which confuses things.

I never use single digit version numbers for this exact reason, would have had 4.04 and 4.19 or gone from 4.9 to 5.0 and carried on from there.
Haha. Thanks so much for this reminder you cannot assume how version numbers count.

https://www.kernel.org/category/releases.html

I see now I got impatient and frustrated before thinking it through.

Thanks everyone for your answers.

Re: Kernel 4.19 - USB Gadget? Do I need to upgrade? How do Kernel versions work?

Posted: Fri Dec 06, 2019 8:27 pm
by DougieLawson
robear wrote:
Fri Dec 06, 2019 5:15 pm
My issue is not understanding the version numbering system it appears. The poster above mentions 4.19 is newer than 4.4. I am sure you understand this is not intuitive? I have attempted googling for specific information about this and could not find a list of kernel versions and release date, or some sort of way to relate the linux kernel number to these raspbian release numbers. Are they the same?
The number is Version.Release.Modification level (also known as V.R.M)
So 4.4.x is shorthand for Version 4, release 4, mod x
and 4.19.x is Version 4, release 19, mod x (same version higher release and therefore newer and more current).

Sorry that it's not obvious to you. It's second nature to me.

There is no change log as such, only 750000 commits of code changes at: https://github.com/raspberrypi/linux/commits/rpi-4.19.y