Re: [Xen-devel] [PATCH v3 00/11] xen: Initial kexec/kdump implementation

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2013-01-04 at 14:22 +0000, Daniel Kiper wrote:
> On Wed, Jan 02, 2013 at 11:26:43AM +0000, Andrew Cooper wrote:
> > On 27/12/12 18:02, Eric W. Biederman wrote:
> > >Andrew Cooper<andrew.cooper3@xxxxxxxxxx>  writes:
> > >
> > >>On 27/12/2012 07:53, Eric W. Biederman wrote:
> > >>>The syscall ABI still has the wrong semantics.
> > >>>
> > >>>Aka totally unmaintainable and umergeable.
> > >>>
> > >>>The concept of domU support is also strange.  What does domU support 
> > >>>even mean, when the dom0 support is loading a kernel to pick up Xen when 
> > >>>Xen falls over.
> > >>There are two requirements pulling at this patch series, but I agree
> > >>that we need to clarify them.
> > >It probably make sense to split them apart a little even.
> > >
> > >
> >
> > Thinking about this split, there might be a way to simply it even more.
> >
> > /sbin/kexec can load the "Xen" crash kernel itself by issuing
> > hypercalls using /dev/xen/privcmd.  This would remove the need for
> > the dom0 kernel to distinguish between loading a crash kernel for
> > itself and loading a kernel for Xen.
> >
> > Or is this just a silly idea complicating the matter?
> 
> This is impossible with current Xen kexec/kdump interface.
> It should be changed to do that. However, I suppose that
> Xen community would not be interested in such changes.

The current HYPERVISOR_kexec interface is pretty fricken bad (it
basically hardcodes the Linux Circa-2.6.18 internal interface!).

I'd be all for a new HYPERVISOR_kexec (with the old gaining a _compat
suffix) which implements something more generic that isn't tied to a
particular dom0 kernel implementation (be it differing versions of Linux
or e.g. *BSD).

If that enables /sbin/kexec to load the kernel directly then so much the
better, assuming the /sbin/kexec maintainers are happy with that
approach.

Ian.


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