Re: [PATCH] x86: Find offset for crashkernel reservation automatically

From: Yinghai Lu
Date: Mon Jul 14 2008 - 13:06:59 EST


On Mon, Jul 14, 2008 at 2:44 AM, Eric W. Biederman
<ebiederm@xxxxxxxxxxxx> wrote:
> Bernhard Walle <bwalle@xxxxxxx> 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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