I've a question regarding the building of the linux kernel, more specifically which kernel to build. I've previously built the kernel for an 86 arch but this time I want to build for the RaspberryPi. I can easily get the current version of the installed kernel with the "uname -a" command but that doesn't tell me the git repo where the kernel originated. I'd imagine that it's from the RPi git repo, but that adds another level of confusion as that git repo doesn't have any tags at all. So even given the version number from uname how to check out a suitable version of the kernel. I could take the latest from the RPi repo and use "make oldconfig" but I wonder how far, in kernel versions, I can jump and not affect the installed libs and utilities which have been built against another version of the kernel? I've read various documentation on building the linux kernel but that's never really mentioned, mainly I guess as you're building for the x86 Arch. But even there can you jump major versions of kernel without effecting other installed SW in the system? John
On Sun, Jun 14, 2015 at 10:11 AM, John Whitmore <arigead@gmail.com> wrote:
I've a question regarding the building of the linux kernel, more specifically which kernel to build.
I've previously built the kernel for an 86 arch but this time I want to build for the RaspberryPi. I can easily get the current version of the installed kernel with the "uname -a" command but that doesn't tell me the git repo where the kernel originated. I'd imagine that it's from the RPi git repo, but that adds another level of confusion as that git repo doesn't have any tags at all. So even given the version number from uname how to check out a suitable version of the kernel.
Did you read the https://www.raspberrypi.org/documentation/linux/kernel/building.md ? There is a few tags : https://github.com/raspberrypi/linux/releases
I could take the latest from the RPi repo and use "make oldconfig" but I wonder how far, in kernel versions, I can jump and not affect the installed libs and utilities which have been built against another version of the kernel?
The problem is not the user space programs, it's really if the newer kernel will boot in your hardware. If you use the RPi kernel, you can use the lasted kernel without problems, but if you use the mainline kernel (Linus) you will have a few problems. Just because it doesn't have all the modifications made on RPi kernel.
I've read various documentation on building the linux kernel but that's never really mentioned, mainly I guess as you're building for the x86 Arch. But even there can you jump major versions of kernel without effecting other installed SW in the system?
If you read this docs you are able to test different kernel versions without problems. So go test it. More info at : http://elinux.org/Raspberry_Pi_Kernel_Compilation
John
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On Sun, Jun 14, 2015 at 02:11:33PM +0100, John Whitmore wrote:
I've a question regarding the building of the linux kernel, more specifically which kernel to build.
Always the latest version, why would you want to build an old one?
I've previously built the kernel for an 86 arch but this time I want to build for the RaspberryPi. I can easily get the current version of the installed kernel with the "uname -a" command but that doesn't tell me the git repo where the kernel originated. I'd imagine that it's from the RPi git repo, but that adds another level of confusion as that git repo doesn't have any tags at all. So even given the version number from uname how to check out a suitable version of the kernel.
If you are using hardware that is not completly supported in the main kernel.org repo, like many embedded devices like the RPi, I suggest using the source repo that the project provides instead.
I could take the latest from the RPi repo and use "make oldconfig" but I wonder how far, in kernel versions, I can jump and not affect the installed libs and utilities which have been built against another version of the kernel?
You should always be able to use a new kernel on old userspace with no problems. Going backwards is not supported (old kernel on new userspace.) hope this helps, greg k-h
On Sun, Jun 14, 2015 at 08:27:03AM -0700, Greg KH wrote:
On Sun, Jun 14, 2015 at 02:11:33PM +0100, John Whitmore wrote:
I've a question regarding the building of the linux kernel, more specifically which kernel to build.
Always the latest version, why would you want to build an old one?
I've previously built the kernel for an 86 arch but this time I want to build for the RaspberryPi. I can easily get the current version of the installed kernel with the "uname -a" command but that doesn't tell me the git repo where the kernel originated. I'd imagine that it's from the RPi git repo, but that adds another level of confusion as that git repo doesn't have any tags at all. So even given the version number from uname how to check out a suitable version of the kernel.
If you are using hardware that is not completly supported in the main kernel.org repo, like many embedded devices like the RPi, I suggest using the source repo that the project provides instead.
I could take the latest from the RPi repo and use "make oldconfig" but I wonder how far, in kernel versions, I can jump and not affect the installed libs and utilities which have been built against another version of the kernel?
You should always be able to use a new kernel on old userspace with no problems. Going backwards is not supported (old kernel on new userspace.)
hope this helps,
greg k-h
Yes that clears up versions, thanks a milion. John
participants (3)
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Greg KH -
John Whitmore -
Lucas Tanure