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

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Date:   Tue, 6 Oct 2020 09:30:38 +0800
From:   chenzhou <chenzhou10@...wei.com>
To:     Catalin Marinas <catalin.marinas@....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 2020/10/6 1:16, Catalin Marinas wrote:
> 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?
Yes，just pick the high region and will boot fail if low memory is needed.

Thanks,
Chen Zhou
>