Re: Changing the destination Linux Kernel version

["Yann E. MORIN" <yann dot morin dot 1998 at free dot fr>]

Johannes, Clément, All,

On Monday 25 March 2013 Johannes Stezenbach wrote:
> On Sun, Mar 24, 2013 at 06:09:10PM +0100, Yann E. MORIN wrote:
> > On Sunday 24 March 2013 Clément VERMOT-DESROCHES wrote:
> > > On Wed, Mar 13, 2013 at 8:49 PM, Johannes Stezenbach <js@sig21.net> wrote:
> > > >
> > > > The "for GNU/Linux 2.6.24" is determined by the glibc of your
> > > > build machine, you cannot change it by any compile
> > > > or link options.
> > > >
> > > Ok for this point.
> > 
> > You have to tell at build-time (the toolchain build-time) what your oldest
> > running kernel will be:
> >     C-library  -->
> >         Minimum supported kernel version  -->
> >             (Specific kernel version)
> >         (2.6.9) Minimum kernel version to support
> > 
> > Change '2.6.9' with the oldest kernel you'll be running on the target.
> 
> We're talking about about the "host" (where the toolchain should
> run) not about the target, and not about the "build" machine
> (where the toolchain is built).

Ah, OK.

If I were to build such a toolchain, I would build a canadian-cross.
Here's how I-d do it:

 0) Install a recent distro (on a physical nachine, or in a VM);
 1) Build  a cross-compiler that targets your old machine, using the
    "minimum kernel version" trick I demomnstrated in my previous mail;
 2) Build a static canadian-cross whose host would be the old machine,
    and would be built using the cross-compiler just above;
 3) Deploy that canadian cros to the old machine.

So, as it is statically-linked, and the glibc that was used to build it has
support for an old kernel, the toolchain would run on your old machine.

Regards,
Yann E. MORIN.

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