Re: [PATCH v1 2/2] xen/arm: Enlarge identity map space to 127TiB

[Leo Yan <leo.yan@xxxxxxxxxx>]

Hi Bertrand,

On Mon, Sep 04, 2023 at 01:55:12PM +0000, Bertrand Marquis wrote:
> Hi Leo,
> 
> > On 31 Aug 2023, at 13:01, Leo Yan <leo.yan@xxxxxxxxxx> wrote:
> > 
> > On some platforms, the memory regions could be:
> > 
> >  (XEN) MODULE[0]: 00000807f6df0000 - 00000807f6f3e000 Xen
> >  (XEN) MODULE[1]: 00000807f8054000 - 00000807f8056000 Device Tree
> >  (XEN) MODULE[2]: 00000000fa834000 - 00000000fc5de1d5 Ramdisk
> >  (XEN) MODULE[3]: 00000000fc5df000 - 00000000ffb3f810 Kernel
> > 
> > In this case, the Xen binary is loaded above 2TB, so Xen fails to boot
> > up due to the out of the identity map space.
> > 
> > This patch enlarges identity map space to 127TiB, which can support the
> > memory space [0x0 .. 0x00007eff_ffff_ffff], thus it has flexibility for
> > support different platforms.
> > 
> > Fixes: 1c78d76b67 ("xen/arm64: mm: Introduce helpers to 
> > prepare/enable/disable")
> > Reported-by: Alexey Klimov <alexey.klimov@xxxxxxxxxx>
> > Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
> 
> This is not based on the current status of staging where this part of the
> code was modified.
> 
> Currently Xen virtual address is at 2TB and the extension you are making
> will potentially make it possible to load Xen at 2TB which will clash for the
> identity mapping handling in Xen.

I will check the stage code if this patch will introduce any clash
with the identity mapping handling.

> Please rebase on the latest staging and check there how you can do as
> this patch if rebased on staging right now with rightfully end in a 
> compilation
> error.

Sure, I will rebase on the latest staging branch.

Thank you for suggestions.

Leo