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Message-ID: <86802c440807141006o98afac8t66b0933d8acd2746@mail.gmail.com>
Date: Mon, 14 Jul 2008 10:06:48 -0700
From: "Yinghai Lu" <yhlu.kernel@gmail.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH] x86: Find offset for crashkernel reservation automatically
Cc: "Bernhard Walle" <bwalle@suse.de>, "Vivek Goyal" <vgoyal@redhat.com>,
       kexec@lists.infradead.org, x86@kernel.org, linux-kernel@vger.kernel.org
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On Mon, Jul 14, 2008 at 2:44 AM, Eric W. Biederman
<ebiederm@xmission.com> wrote:
> Bernhard Walle <bwalle@suse.de> writes:
>
>> * Yinghai Lu [2008-07-14 00:11]:
>>>
>>> should use min_t(u64, 1ULL<<32, max_low_pfn<<PAGE_SHIFT) replace ULONG_MAX
>>
>> Shouldn't we use  min_t(u64, ULLONG_MAX, max_low_pfn<<PAGE_SHIFT), i.e.
>> should we really limit the crashkernel to a 32 bit address on a 64 bit
>> system?
>
> We should use the lowest physical address that meets our size and
> alignment constraints.  However there is no reason to make this be <
> 4G or even < 1G.  The worst case is that we reserve an area the kdump
> kernel can't run out of.  However /sbin/kexec should check for that as
> the kexec on panic code is not necessarily a linux kernel.

for 64bit, kdump can start from address above 4g with bzImage?

YH
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