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

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Message-ID: <20190128101831.GA27154@zn.tnic>
Date:   Mon, 28 Jan 2019 11:18:31 +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 Mon, Jan 28, 2019 at 05:58:09PM +0800, Dave Young wrote:
> Another reason is in case ,high we will need automatically reserve a
> region in low area for swiotlb.  So for example one use
> crashkernel=256M,high,  actual reserved memory is 256M above 4G and
> another 256M under 4G for swiotlb.  Normally it is not necessary for
> most people.  Thus we can not make ,high as default.

And how is the poor user to figure out that we decided for her/him that
swiotlb reservation is something not necessary for most people and thus
we fail the crashkernel= reservation?

IOW, that "logic" above doesn't make a whole lot of sense to me from
user friendliness perspective.

-- 
Regards/Gruss,
    Boris.

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