linux-kernel - Re: [PATCH v12 6/9] arm64: kdump: reimplement crashkernel=X

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Date:   Mon, 5 Oct 2020 18:16:08 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Chen Zhou <chenzhou10@...wei.com>
Cc:     will@...nel.org, james.morse@....com, tglx@...utronix.de,
        mingo@...hat.com, dyoung@...hat.com, bhe@...hat.com,
        corbet@....net, John.P.donnelly@...cle.com,
        prabhakar.pkin@...il.com, bhsharma@...hat.com, horms@...ge.net.au,
        robh+dt@...nel.org, arnd@...db.de, nsaenzjulienne@...e.de,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kexec@...ts.infradead.org, linux-doc@...r.kernel.org,
        guohanjun@...wei.com, xiexiuqi@...wei.com, huawei.libin@...wei.com,
        wangkefeng.wang@...wei.com
Subject: Re: [PATCH v12 6/9] arm64: kdump: reimplement crashkernel=X

On Mon, Sep 07, 2020 at 09:47:42PM +0800, Chen Zhou wrote:
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 53acbeca4f57..1b24072f2bae 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -238,7 +238,18 @@ static void __init request_standard_resources(void)
>  		    kernel_data.end <= res->end)
>  			request_resource(res, &kernel_data);
>  #ifdef CONFIG_KEXEC_CORE
> -		/* Userspace will find "Crash kernel" region in /proc/iomem. */
> +		/*
> +		 * Userspace will find "Crash kernel" or "Crash kernel (low)"
> +		 * region in /proc/iomem.
> +		 * In order to distinct from the high region and make no effect
> +		 * to the use of existing kexec-tools, rename the low region as
> +		 * "Crash kernel (low)".
> +		 */
> +		if (crashk_low_res.end && crashk_low_res.start >= res->start &&
> +				crashk_low_res.end <= res->end) {
> +			crashk_low_res.name = "Crash kernel (low)";
> +			request_resource(res, &crashk_low_res);
> +		}

With the changes in this series (including the above), how do the
current kexec-tools behave? Do they pick just the high region and the
loaded kernel will subsequently fail to boot?

-- 
Catalin