Re: [PATCH 2/3] x86: add a is_e820_ram() helper

From: Christoph Hellwig
Date: Fri Mar 27 2015 - 04:10:21 EST

On Thu, Mar 26, 2015 at 03:59:28PM -0700, Yinghai Lu wrote:
> What do you want to get here?
> You did not modify memblock_x86_fill() to treat
> E820_PRAM as E820_RAM, so memblock will not have any
> entry for E820_PRAM, so you do not need to call memblock_reserve
> there.
> And the same time, init_memory_mapping() will call
> init_range_memory_mapping/for_each_mem_pfn_range() to
> set kernel mapping for memory range in memblock only.
> So here calling init_memory_mapping will not do anything.
> then just drop calling to that init_memory_mapping.
> --- so will not kernel mapping pmem, is that what you intended to have?

I think the intent of the old Intel code was to indeed map the pmem
into KVA space. That got broken when I forward ported it to use
memblocks. However the current pmem infrastructure doesn't need the
KVA mapping, so I can remove it for now.

However we have heated discussions about how to do I/O to pmem, and
KVA mapping is one of the options. If we got with that option I might
bring this code back in a fixed up version.
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