RE: [RFC Patch 2/2] kexec: allow to shrink reserved memory

Yu, Fenghua
2009-08-11T20:55:16Z

>On Tue, Aug 11, 2009 at 06:39:32AM -0400, Amerigo Wang wrote:
>>
>> This patch implements shrinking the reserved memory for crash kernel,
>> if it is more than enough.
>>
>> For example, if you have already reserved 128M, now you just want 100M,
>> you can do:
>>
>> # echo $((100*1024*1024)) > /sys/kernel/kexec_crash_size
>>
>> Signed-off-by: WANG Cong <amwang@redhat.com>
>> Cc: Neil Horman <nhorman@redhat.com>
>> Cc: Eric W. Biederman <ebiederm@xmission.com>
>> Cc: Andi Kleen <andi@firstfloor.org>
>>
>
>Since the reserved area is also used for heap in the new kernel, isn't this
>mechanism going to guarantee a non-bootable kernel. It seems like it
>shrinks
>the reserved area to the size of the image, leaving no additional memory
>for
>heap allocations during the kernels boot. Or am I missing something?

I think this mechanism need user to have the intelligence to decide the size of memory reserved for crashed kernel. The crash kernel size should include all space a crashed kernel need. This mechanism just does whatever crashed kernel size the user specifies.

Thanks.

-Fenghua