From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <1394153258.21206.1.camel@concordia> Subject: Re: [PATCH] kexec/powerpc: fix exporting memory limit From: Michael Ellerman To: Nikita Yushchenko Date: Fri, 07 Mar 2014 11:47:38 +1100 In-Reply-To: <1394115854-11709-1-git-send-email-nyushchenko@dev.rtsoft.ru> References: <1394115854-11709-1-git-send-email-nyushchenko@dev.rtsoft.ru> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: yadviga@dev.rtsoft.ru, lugovskoy@dev.rtsoft.ru, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Paul Mackerras , Anton Blanchard , Mahesh Salgaonkar , Hari Bathini , linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2014-03-06 at 18:24 +0400, Nikita Yushchenko wrote: > When preparing dump-capturing kernel, kexec userspace tool needs to know > actual amount of memory used by the running kernel. This may differ from > extire available DRAM for a couple of reasons. To address this issue, > kdump kernel support code injects several attributes into device tree that > are later captured by userspace kexec tool via /proc interface. > > One such attrubute is 'chosen/linux,memory_limit' that is used to pass > memory limit of the running kernel. > > This was initialized using kernel's 'memory_limit' variable, that is set > by early init code based on mem= kernel parameter and other reasons. > > But there are cases when memory_limit variable does not contain proper > information. One such case is when !CONFIG_HIGHMEM kernel runs on system > with memory large enough not to fit into lowmem. Why doesn't the !CONFIG_HIGHMEM code update memory_limit to reflect reality. cheers