linux-kernel - Re: [PATCH 0/3] ARM: Use generic interface to simplify crashkernel reservation

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Message-ID: <01869981-b1de-32cb-bd25-d6ea09752b3d@huawei.com>
Date: Tue, 9 Jul 2024 19:06:09 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: Baoquan He <bhe@...hat.com>
CC: <linux@...linux.org.uk>, <vgoyal@...hat.com>, <dyoung@...hat.com>,
	<paul.walmsley@...ive.com>, <palmer@...belt.com>, <aou@...s.berkeley.edu>,
	<arnd@...db.de>, <afd@...com>, <akpm@...ux-foundation.org>,
	<rmk+kernel@...linux.org.uk>, <linus.walleij@...aro.org>,
	<eric.devolder@...cle.com>, <gregkh@...uxfoundation.org>, <deller@....de>,
	<javierm@...hat.com>, <robh@...nel.org>, <thunder.leizhen@...wei.com>,
	<austindh.kim@...il.com>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <kexec@...ts.infradead.org>
Subject: Re: [PATCH 0/3] ARM: Use generic interface to simplify crashkernel
 reservation



On 2024/7/9 18:39, Baoquan He wrote:
> On 07/09/24 at 05:50pm, Jinjie Ruan wrote:
>>
>>
>> On 2024/7/9 17:29, Baoquan He wrote:
>>> On 07/08/24 at 09:33pm, Jinjie Ruan wrote:
>>>> Currently, x86, arm64, riscv and loongarch has been switched to generic
>>>> crashkernel reservation. Also use generic interface to simplify crashkernel
>>>> reservation for arm32, and fix two bugs by the way.
>>>
>>> I am not sure if this is a good idea. I added the generic reservation
>>> itnerfaces for ARCH which support crashkernel=,high|low and normal
>>> crashkernel reservation, with this, the code can be simplified a lot.
>>> However, arm32 doesn't support crashkernel=,high, I am not sure if it's
>>> worth taking the change, most importantly, if it will cause
>>> misunderstanding or misoperation.
>>
>> Yes, arm32 doesn't support crashkernel=,high.
>>
>> However, a little enhancement to the generic code (please see the first
>> patch), the generic reservation interfaces can also be applicable to
>> architectures that do not support "high" such as arm32, and it can also
>> simplify the code (please see the third patch).
> 
> Yeah, I can see the code is simplified. When you specified
> 'crashkernel=xM,high', do you think what should be warn out? Because
> it's an unsupported syntax on arm32, we should do something to print out
> appropriate message.

Yes, you are right! In this patch it will print "crashkernel high memory
reservation failed." message and out for arm32 if you specify
'crashkernel=xM,high because "CRASH_ADDR_LOW_MAX" and
"CRASH_ADDR_HIGH_MAX" is identical for arm32. And it should also warn
out for other similar architecture.


> 
>