Re: [RFC 0/2] Delay initializing of large sections of memory

From: H. Peter Anvin
Date: Tue Jun 25 2013 - 15:09:38 EST


On 06/25/2013 12:03 PM, Yinghai Lu wrote:
>> It is worth experimenting with but the big question would be,
>> if it still avoids the very expensive "memmap_init_zone" and
>> it's sub-functions using huge expanses of memory. I'll do some
>> experimenting as soon as I can. Our 32TB system is being
>> brought back to 16TB (we found a number of problems as we
>> get closer and closer to the 64TB limit), but that's still
>> a significant size.
>
> According to Intel SDM, CPU could support 52bits physical addressing.
>
> So how linux kernel will handle it? as we only have 48bits virtual addressing.
>

The Linux kernel will not support more than V-2 bits of physical address
space for any number V of virtual address bits.

-hpa


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