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Date: Thu, 11 Mar 2010 13:42:42 -0800
From: Yinghai Lu <yinghai@kernel.org>
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To: Jiri Slaby <jirislaby@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>,
       Johannes Weiner <hannes@cmpxchg.org>, Greg Thelen <gthelen@google.com>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       Ingo Molnar <mingo@elte.hu>, "H. Peter Anvin" <hpa@zytor.com>,
       Thomas Gleixner <tglx@linutronix.de>, cl@linux-foundation.com
Subject: Re: mmotm boot panic bootmem-avoid-dma32-zone-by-default.patch
References: <49b004811003041321g2567bac8yb73235be32a27e7c@mail.gmail.com> <20100305032106.GA12065@cmpxchg.org> <4B90C921.6060908@kernel.org> <4B90DC3C.1060000@gmail.com> <4B92FE9E.90600@kernel.org> <4B98CBC8.6080008@gmail.com> <4B994EC4.2050705@kernel.org> <4B996335.7070907@gmail.com>
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On 03/11/2010 01:40 PM, Jiri Slaby wrote:
> On 03/11/2010 09:12 PM, Yinghai Lu wrote:
>> On 03/11/2010 02:54 AM, Jiri Slaby wrote:
>>> Hi, yes, it is 2.6.27.
>>
>> SLES 11?
> 
> Sorry I wrote that in haste. It is SLES 10 in the end. That means it is
> 2.6.16, not 2.6.27. Hence no sparsemem whatsoever. With SLES11 it should
> be OK, we are using flatmem only for i386.
> 
> Whatever, it should be no issue now, as flatmem currently (as of 2.6.25)
> depends on i386.
> 
> On the other hand I still considered the patch as applicable to
> contemporary kernels since there might be weird bios e820 maps and huge
> (and sparse) bootmem allocations/reservations (memory cgroups, initrd)
> so that code requiring much memory below 4g (swiotlb) will fail then.
> 
> Whatever, in the current kernel, the particular issue I was referring to
> *is not reproducible*.

the point is: we should only put the memmap put high. that is big chunk...
other users should be ok... and leave them alone. 

YH