linux-kernel - Re: [PATCHv7] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr

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Message-ID: <20190125140823.GC27998@zn.tnic>
Date:   Fri, 25 Jan 2019 15:08:23 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Dave Young <dyoung@...hat.com>
Cc:     Pingfan Liu <kernelfans@...il.com>, kexec@...ts.infradead.org,
        Baoquan He <bhe@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>, yinghai@...nel.org,
        vgoyal@...hat.com, Randy Dunlap <rdunlap@...radead.org>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv7] x86/kdump: bugfix, make the behavior of crashkernel=X
 consistent with kaslr

On Fri, Jan 25, 2019 at 09:45:18PM +0800, Dave Young wrote:
> AFAIK, some people prefer to explictly reserve crash memory at high
> region even if it is possible to reserve at low area.  May because
> <4G memory is limited on large server, they want to leave this for other
> use. 
> 
> Yinghai or Vivek should know more about the history, probably they can
> recall some initial reason.

Yes, just "prefer" is not good enough. There should be a technical
reason why that's there.

Also, if the user doesn't care, then the code should be free to force
"high" and thus probe a different range for allocation.

> Good question, still it may be some historical reason, but it is good to
> make them clear and rethink about it after long time.
> 
> I also want to understand, need dig the log more.

Good idea. That would be a very nice cleanup. :-)

Thx.

-- 
Regards/Gruss,
    Boris.

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