From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Date: Thu, 22 Oct 2015 11:25:34 +0800 From: Dave Young Subject: Re: [PATCH 13/16] arm64: kdump: add kdump support Message-ID: <20151022032534.GC11227@dhcp-129-115.nay.redhat.com> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Geoff Levand Cc: Mark Rutland , AKASHI@infradead.org, marc.zyngier@arm.com, Catalin Marinas , Will Deacon , Takahiro , christoffer.dall@linaro.org, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org Hi, AKASHI, On 10/19/15 at 11:38pm, Geoff Levand wrote: > From: AKASHI Takahiro > > On crash dump kernel, all the information about primary kernel's core > image is available in elf core header specified by "elfcorehdr=" boot > parameter. reserve_elfcorehdr() will set aside the region to avoid any > corruption by crash dump kernel. > > Crash dump kernel will access the system memory of primary kernel via > copy_oldmem_page(), which reads one page by ioremap'ing it since it does > not reside in linear mapping on crash dump kernel. > Please note that we should add "mem=X[MG]" boot parameter to limit the > memory size and avoid the following assertion at ioremap(): > if (WARN_ON(pfn_valid(__phys_to_pfn(phys_addr)))) > return NULL; > when accessing any pages beyond the usable memories of crash dump kernel. How does kexec-tools pass usable memory ranges to kernel? using dtb? Passing an extra mem=X sounds odd in the design. Kdump kernel should get usable ranges and hanle the limit better than depending on an extern kernel param. Thanks Dave _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec