[oe] arm kexec commandline support

[Hans Henry von Tresckow]

On 9/27/07, Mike (mwester) <mwester at dls.net> wrote:
>
> Bob Dunlop, on September 27, 2007, wrote:
> > Hans Henry von Tresckow wrote:
> > >On 6/7/07, Thomas Kunze <thommycheck at gmx.de> wrote:
> > ...
> > >> I have written a quick hack to support custom commandlines for arm
> with
> > >> kexec. You need:
> > >>
> > >>
> > >>
>
> http://www2.informatik.hu-berlin.de/~tkunze/zaurus/patches/kexec_commandline-3.patch
> > >>
> > >> and:
> > >>
> > >>
> > >>
>
> http://www2.informatik.hu-berlin.de/~tkunze/zaurus/patches/atag_support.patch
> > >>
> > >> (from lak)
> > ...
> > >
> > >I  tested this  with linux-rp-2.6.20 on poodle. The kernel will boot
> and
> I
> > >can kexec other kernels with built in cmdlines. If I try to set a new
> > >cmdline however, it segfaults. Here is the crash dump:
> > >
> > ><0>Starting new kernel
> > ><1>Unable to handle kernel paging request at virtual address e0000100
> >
> > I to am searching for a kexec solution (for a Compulab CM-X270)
> >
> > I can progress this code a little further and eliminate the segfault
> with
> > the following patch, but still nothing after the final Bye! message :(
> >
> [patch snipped]
>
> Permit me to pop into this thread.   At the risk of covering old ground, I
> believe that the discussion on L-A-K ended with the general conscensus
> that
> the preferred approach was to use the "preserve-original-atags" patch [1],
> and write something new that would permit the user-space "kexec" command
> to
> edit/replace/remove the preserved atags.
>
> The first half of this is done -- it's been submitted upstream (since it
> is
> a useful patch in and of itself even without the ability to change
> command-lines, permitting kexec to actually work on machines that require
> bootloader atags, such as the OpenMoko distro on the Neo).
>
> The second half has not been started, but probably should begin with Uli's
> work with the kexec command, I would expect.
>
> The advantage of this approach is that the first patch takes care of all
> the
> ugly stuff that result in seg faults, and other horrors.  All that is
> required for the second half is to use the pointer to the buffer
> containing
> the atags, and replace, or edit, or remove the contents at will.
>
> It's on my list of things to do, but for the moment the sysfs approach,
> while ugly, has worked on all the ARM machines I use.  It would be great
> if
> someone with a bit more spare time could take a hack at the second part of
> this problem.
>
> Regards,
> Mike
>
> [1] http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=4579/1
>
>
> _______________________________________________
> Openembedded-devel mailing list
> Openembedded-devel at lists.openembedded.org
> http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-devel


Thanks for the update mike :)

I am going to play with uli's patch a little bit to see how that will work.
I am glad to see that your main patch made it upstream :)

Thanks,

Henry von Tresckow (hvontres)