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Tue, 09 Jul 2024 23:40:28 -0400 X-MC-Unique: evszWIkEP4igK3S0oBR-Zw-1 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 05811195609E; Wed, 10 Jul 2024 03:40:25 +0000 (UTC) Received: from localhost (unknown [10.72.116.15]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 36E751955F40; Wed, 10 Jul 2024 03:40:21 +0000 (UTC) Date: Wed, 10 Jul 2024 11:40:15 +0800 From: Baoquan He To: Jinjie Ruan Cc: linux@armlinux.org.uk, vgoyal@redhat.com, dyoung@redhat.com, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, arnd@arndb.de, afd@ti.com, akpm@linux-foundation.org, rmk+kernel@armlinux.org.uk, linus.walleij@linaro.org, eric.devolder@oracle.com, gregkh@linuxfoundation.org, deller@gmx.de, javierm@redhat.com, robh@kernel.org, thunder.leizhen@huawei.com, austindh.kim@gmail.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org Subject: Re: [PATCH 0/3] ARM: Use generic interface to simplify crashkernel reservation Message-ID: References: <20240708133348.3592667-1-ruanjinjie@huawei.com> <3157befe-431f-69ac-b9d3-7a8685ba3a4d@huawei.com> <01869981-b1de-32cb-bd25-d6ea09752b3d@huawei.com> <8aed5c59-090b-ea7e-020c-dd2785ee3d7e@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8aed5c59-090b-ea7e-020c-dd2785ee3d7e@huawei.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240709_204039_723396_7A9E8D4B X-CRM114-Status: GOOD ( 28.50 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 07/10/24 at 09:52am, Jinjie Ruan wrote: > > > On 2024/7/9 22:06, Baoquan He wrote: > > On 07/09/24 at 07:06pm, Jinjie Ruan wrote: > >> > >> > >> 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 > > > > That message may mislead people to believe crashkernel=,high is > > supported but reservation is failed, then a bug need be filed for this? > > We may expect a message telling this syntax is not supported on this > > ARCH. > > "CRASH_ADDR_LOW_MAX >= CRASH_ADDR_HIGH_MAX" indicate that the arm32 does > not support "crashkernel=,high", I wonder if this is generic for similar Imagine you are a testing engineer or a distros user, how do you know if "CRASH_ADDR_LOW_MAX >= CRASH_ADDR_HIGH_MAX" when you test 'crashkernel=,high' and see the failure message? > architecture. If so, the first patch can print such as > "crashkernel=,high is not supported on this ARCH" message. Please consider conprehensively if this is doable, you can paste draft code here to prove it. > > > > >> '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. > >> > >> > >>> > >>> > >> > > > > >