Re: [Xen-devel] [PATCH] xen/kexec: Clear unused registers before jumping into an image

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Fri, Nov 15, 2013 at 08:07:02PM +0000, David Vrabel wrote:
> On 15/11/13 15:56, Daniel Kiper wrote:
> > Clear unused registers before jumping into an image. This way
> > loaded image could not assume that any register has an specific
> > info about earlier running Xen hypervisor. However, it also
> > does not mean that the image may expect that a given register
> > is zeroed. The image MUST assume that every register has a random
> > value or in other words it is uninitialized or has undefined state.
>
> I think this, where the specification (registers undefined) differs from
> the implementation (registers zeroed), is the worst option.
>
> I also think it is more likely for an image to inadvertently rely on a
> zero value that whatever junk Xen has left behind.

I do not agree with you but respect your opinion. So could you provide
a patch with a comment why our implementation deviate from our reference
implementation (I think about Linux one) and even we use kexec-tools
designed for Linux implementation which does things mentioned above?
I hope that this solve this last, widely discussed issue.

Daniel

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