Re: [PATCH] x86: 46 bit PAE support

Ingo Molnar
2009-05-06T12:31:04Z

* Rik van Riel <riel@redhat.com> wrote:

> H. Peter Anvin wrote:
>> Rik van Riel wrote:
>>> Testing: booted it on an x86-64 system with 6GB RAM. Did you really think
>>> I had access to a system with 64TB of RAM? :)
>>
>> No, but it would be good if we could test it under Qemu or KVM with an
>> appropriately set up sparse memory map.
>
> I don't have a system with 1TB either, which is how much space
> the memmap[] would take...

Not if the physical layout is sparse. I.e. something silly like:

BIOS-e820: 0000000100000000 - 0000000140000000 (usable)
BIOS-e820: 0000200000000000 - 0000200040000000 (usable)

Which is 1GB of RAM at 4GB physical offset, and another 1GB of RAM
at 32 TB physical offset. Takes two gigs of real RAM and a kernel
modified with your patch, to not get confused by this :-)

Ingo