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

[David Vrabel <david.vrabel@xxxxxxxxxx>]

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.

David

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