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From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Daniel Kiper <dkiper@net-space.pl>
Cc: ian.campbell@citrix.com, akpm@linux-foundation.org,
	andi.kleen@intel.com, haicheng.li@linux.intel.com,
	fengguang.wu@intel.com, jeremy@goop.org, konrad.wilk@oracle.com,
	dan.magenheimer@oracle.com, v.tolstov@selfip.ru, pasik@iki.fi,
	wdauchy@gmail.com, rientjes@google.com,
	xen-devel@lists.xensource.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH 1/4] mm: Remove dependency on CONFIG_FLATMEM from online_page()
Date: Mon, 02 May 2011 14:25:04 -0700	[thread overview]
Message-ID: <1304371504.30823.45.camel@nimitz> (raw)
In-Reply-To: <20110502211915.GB4623@router-fw-old.local.net-space.pl>

On Mon, 2011-05-02 at 23:19 +0200, Daniel Kiper wrote:
> Memory hotplug code strictly depends on CONFIG_SPARSEMEM.
> It means that code depending on CONFIG_FLATMEM in online_page()
> is never compiled. Remove it because it is not needed anymore.

It's subtle, but I don't think that's true.  We had another hotplug mode
for x86_64 before folks were comfortable turning SPARSEMEM on for the
whole architecture.  It was quite possible to have memory hotplug
without sparsemem in that case.  I think Keith Mannthey did some of that
code if I remember right.

But, I'm not sure how much of that stayed in distros versus made it
upstream.  In any case, you might want to chase down the
X86_64_ACPI_NUMA bit to make sure it can't be used with FLATMEM ever.

config MEMORY_HOTPLUG
        bool "Allow for memory hot-add"
        depends on SPARSEMEM || X86_64_ACPI_NUMA
        depends on HOTPLUG && ARCH_ENABLE_MEMORY_HOTPLUG
        depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)

-- Dave

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  reply	other threads:[~2011-05-02 21:25 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-02 21:19 [PATCH 1/4] mm: Remove dependency on CONFIG_FLATMEM from online_page() Daniel Kiper
2011-05-02 21:25 ` Dave Hansen [this message]
2011-05-02 22:18   ` Daniel Kiper
2011-05-02 22:48     ` Dave Hansen
2011-05-11 22:47 ` David Rientjes
2011-05-12 10:25   ` Daniel Kiper
2011-05-12 19:26     ` David Rientjes
2011-05-16  7:58       ` Daniel Kiper
2011-05-16 20:32         ` David Rientjes
2011-05-17  8:46           ` Daniel Kiper
  -- strict thread matches above, loose matches on Subject: below --
2011-05-02 21:19 Daniel Kiper

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