Re: [Xen-devel] [PATCH 18/18] x86: add multiboot2 protocol support for EFI platforms

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Fri, Mar 27, 2015 at 02:34:19PM +0000, Jan Beulich wrote:
> >>> On 27.03.15 at 15:26, <daniel.kiper@xxxxxxxxxx> wrote:
> > On Fri, Mar 27, 2015 at 01:36:32PM +0000, Jan Beulich wrote:
> >> >>> On 27.03.15 at 14:06, <daniel.kiper@xxxxxxxxxx> wrote:
> >> > On Tue, Mar 17, 2015 at 10:32:01AM +0000, Jan Beulich wrote:
> >> >> >>> On 30.01.15 at 18:54, <daniel.kiper@xxxxxxxxxx> wrote:
> >> >> > +        /* Skip Multiboot2 information fixed part */
> >> >> > +        lea     MB2_fixed_sizeof(%ebx),%ecx
> >> >>
> >> >> Let's please not add more assumptions than necessary about stuff
> >> >> being below 4G.
> >> >
> >> > I am not sure what do you mean by that.
> >>
> >> See the 32-bit register used for addressing here (and in many more
> >> places)?
> >
> > This is what I expected but I was confused because you were referring only
> > here to this problem. Anyway, is it possible to do this in different way?
> > Should we care if image is always loaded at 0x100000 right now? Even with
> > Xen early boot code being relocatable loader could not load image higher
> > than 0xffffffff - 14 MiB.
>
> I don't understand what you're alluding to. Just use 64-bit registers
> for memory accesses and LEAs, and be done. This will result in smaller
> code as a benefit.

Well... How can I do that here if processor is in 32-bit mode? Maybe,
we could that things after switching to 64-bit mode. However, I think
this requires separate patch to do these changes.

Daniel

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