Re: [Xen-devel] [PATCH v7 01/14] x86: move xen ELF end of image to 16 MiB

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.09.16 at 23:47, <daniel.kiper@xxxxxxxxxx> wrote:
> It seems that from xen ELF image POV _end symbol properly determine
> image end. However, taking into account that initial Xen image mapping
> covers 16 MiB it looks that it is not sufficient. Currently bootloader
> potentially may load xen ELF image at 1 MiB and let's say put Linux
> kernel or initrd at 8 MiB. Nothing forbids it. This means that initially
> Xen image mapping may cover not only Xen image but also loaded modules.

Okay, up to here you just describe the state of things, which is fine.

> So, let's move end of xen ELF image to 16 MiB. This way we avoid above
> mentioned issue because bootloader will be forced to allocate 15 MiB
> memory region for image. Then it (bootloader) would not be able to put
> in this place anything else because from its POV simply this memory
> region will be allocated and used.

But here you state what the patch does, but not what problem you
solve. And my problem here is that I don't see any problem to be
solved: There may be an overlap of address ranges, but I don't see
that memory being used in two different way. In fact the 16Mb
mapping is just a mapping, without us using anything outside the
Xen image range afaics.

Please clarify.

Jan


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