Building which kernel?

[arigead@gmail.com (John Whitmore)]

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