Re: [RFC PATCH] Introduce persistent memory pool

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Aug 22, 2023 at 11:15:08PM -0700, Stanislav Kinsburskii wrote:
> On Sat, Aug 26, 2023 at 09:45:39AM +0200, Greg Kroah-Hartman wrote:
> > On Tue, Aug 22, 2023 at 06:36:10PM -0700, Stanislav Kinsburskii wrote:
> > > > > +#include <linux/bitmap.h>
> > > > > +#include <linux/memblock.h>
> > > > > +#include <linux/spinlock.h>
> > > > > +#include <linux/types.h>
> > > > > +
> > > > > +#include <linux/pmpool.h>
> > > > > +
> > > > > +#define VERSION			1
> > > > 
> > > > In kernel code does not need versions.
> > > > 
> > > 
> > > Could you elaborate on this? Should kernel version be used as a backward
> > > compatitbility marker instead?
> > 
> > kernel versions should never be checked for in-kernel code, so I really
> > don't understand the question here sorry.
> > 
> > For code that is in the kernel tree, having "versions" on them (as many
> > drivers used to, and now only a few do), makes no sense, especially with
> > the stable/lts trees getting fixes for them over time as well.
> > 
> 
> This version is rather an ABI version. The idea is to make sure, that
> any future ABI change is explicit and reflected in the version, so it
> can be easily noticed in case of kexec to a kernel with an older
> version.
> But I guess there are other ways to make sure, that the ABI contract is
> the preserved.

Which ABI are you referring to here.  The user/kernel one?  Or the
kernel/hypervisor one?  Or something else?

There is no "numbering" of user/kernel apis, sorry.  APIs just don't
need that, you can handle things properly automatically without version
numbers (as again, that just does not work.)

thanks,

greg k-h