Re: [Xen-devel] [BUG 1747]Guest could't find bootable device with memory more than 3600M

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 12.06.13 at 16:02, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
> Il 12/06/2013 09:49, Jan Beulich ha scritto:
>>> #3 should be possible or even the default (would need to check), but #4
>>> is probably a bit harder to do.  Perhaps you can use a magic I/O port
>>> for the xen platform PV driver, but if you can simply use two PCI
>>> windows it would be much simpler because that's the same that TCG and
>>> KVM already do.  The code is all there for you to lift in SeaBIOS.
>> 
>> What is the connection here to the platform PV driver?
> 
> It's just a hook you already have for Xen-specific stuff in QEMU.

Oh, sorry, I'm generally taking this term to refer to a Linux
component.

>>> Only Windows XP and older had problems with that because they didn't
>>> like something in the ASL; but the 64-bit window is placed at the end of
>>> RAM, so in principle any PAE-enabled OS can use it.
>> 
>> At the end of _RAM_???
> 
> Why the question marks? :)

Ah, so mean right after RAM. "At the end of RAM" reads like
overlapping (and discarding) the tail of it.

> If you have 4GB of RAM it will end at 0x140000000 (or something like
> that) and that's where the 64-bit window starts.  Of course if you have
> no RAM above the PCI hole, the 64-bit window will start at 0x100000000.

So there's no provision whatsoever for extending the amount of RAM
a guest may see? This is why I'd see any such allocation strategy to
start at the end of physical address space, moving downwards.

Jan


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