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Subject: Re: [PATCH v2 0/5] Allocate memmap from hotadded memory
From:   Rashmica Gupta <rashmica.g@gmail.com>
To:     Michal Hocko <mhocko@kernel.org>
Cc:     Oscar Salvador <osalvador@suse.de>,
        David Hildenbrand <david@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dan Williams <dan.j.williams@intel.com>,
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        anshuman.khandual@arm.com, Vlastimil Babka <vbabka@suse.cz>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Date:   Thu, 01 Aug 2019 09:06:40 +1000
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On Wed, 2019-07-31 at 14:08 +0200, Michal Hocko wrote:
> On Tue 02-07-19 18:52:01, Rashmica Gupta wrote:
> [...]
> > > 2) Why it was designed, what is the goal of the interface?
> > > 3) When it is supposed to be used?
> > > 
> > > 
> > There is a hardware debugging facility (htm) on some power chips.
> > To use
> > this you need a contiguous portion of memory for the output to be
> > dumped
> > to - and we obviously don't want this memory to be simultaneously
> > used by
> > the kernel.
> 
> How much memory are we talking about here? Just curious.

From what I've seen a couple of GB per node, so maybe 2-10GB total.