From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Date: Tue, 4 Oct 2016 11:18:33 +0100 From: Mark Rutland Subject: Re: [PATCH v26 0/7] arm64: add kdump support Message-ID: <20161004101833.GB18083@leverpostej> References: <20160907042908.6232-1-takahiro.akashi@linaro.org> <8a57223d-000d-536e-6885-d427ee81508c@caviumnetworks.com> <20161003110424.GD14025@linaro.org> <1ae717d6-b2aa-105b-4f47-d879882ca5d3@caviumnetworks.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1ae717d6-b2aa-105b-4f47-d879882ca5d3@caviumnetworks.com> 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: Manish Jaggi Cc: geoff@infradead.org, kexec@lists.infradead.org, will.deacon@arm.com, "Kapoor, Prasun" , AKASHI Takahiro , james.morse@arm.com, catalin.marinas@arm.com, bauerman@linux.vnet.ibm.com, dyoung@redhat.com, linux-arm-kernel@lists.infradead.org On Mon, Oct 03, 2016 at 06:11:40PM +0530, Manish Jaggi wrote: > On 10/03/2016 04:34 PM, AKASHI Takahiro wrote: > > On Mon, Oct 03, 2016 at 01:24:34PM +0530, Manish Jaggi wrote: > >> Observations: > >> 1.1. Dump capture kernel shows different memory map. > >> --------------------------------------------------- > >> In dump capture kernel /proc/meminfo and /proc/iomem differ > >> > >> root@arm64:/home/ubuntu/CODE/crash# > >> MemTotal: 65882432 kB > >> MemFree: 65507136 kB > >> MemAvailable: 60373632 kB > >> Buffers: 29248 kB > >> Cached: 46720 kB > >> SwapCached: 0 kB > >> Active: 63872 kB > >> Inactive: 19776 kB > >> Active(anon): 8256 kB > >> Inactive(anon): 7616 kB > >> > >> First kernel is booted with mem=2G crashkernel=1G command line option. > >> While the system has 64G memory. > >> > >> root@arm64:/home/ubuntu/CODE/crash# cat /proc/iomem > >> 41400000-fffeffff : System RAM > >> 41480000-420cffff : Kernel code > >> 42490000-4278ffff : Kernel data > >> ffff0000-ffffffff : reserved > >> 100000000-ffaa7ffff : System RAM > >> ffaa80000-ffaabffff : reserved > >> ffaac0000-fffa6ffff : System RAM > >> fffa70000-fffacffff : reserved > >> fffad0000-fffffffff : System RAM > > > > Are you saying that "mem=..." doesn't have any effect? > What I am saying it that If the first kernel is booted using mem= option and crashkernel= option > the memory for second kernel has to be withing the crashkernel size. Please don't try to use mem= to limit the kernel to a specific range of memory. It's really only there as a tool to test handling of low-memory situations. While it guarantees that at most, the amount requested will be used (modulo a number of edge cases with reserved memory ranges), it does not guarantee *which* memory will be used. It is *very* fragile. Thanks, Mark. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Tue, 4 Oct 2016 11:18:33 +0100 Subject: [PATCH v26 0/7] arm64: add kdump support In-Reply-To: <1ae717d6-b2aa-105b-4f47-d879882ca5d3@caviumnetworks.com> References: <20160907042908.6232-1-takahiro.akashi@linaro.org> <8a57223d-000d-536e-6885-d427ee81508c@caviumnetworks.com> <20161003110424.GD14025@linaro.org> <1ae717d6-b2aa-105b-4f47-d879882ca5d3@caviumnetworks.com> Message-ID: <20161004101833.GB18083@leverpostej> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Oct 03, 2016 at 06:11:40PM +0530, Manish Jaggi wrote: > On 10/03/2016 04:34 PM, AKASHI Takahiro wrote: > > On Mon, Oct 03, 2016 at 01:24:34PM +0530, Manish Jaggi wrote: > >> Observations: > >> 1.1. Dump capture kernel shows different memory map. > >> --------------------------------------------------- > >> In dump capture kernel /proc/meminfo and /proc/iomem differ > >> > >> root at arm64:/home/ubuntu/CODE/crash# > >> MemTotal: 65882432 kB > >> MemFree: 65507136 kB > >> MemAvailable: 60373632 kB > >> Buffers: 29248 kB > >> Cached: 46720 kB > >> SwapCached: 0 kB > >> Active: 63872 kB > >> Inactive: 19776 kB > >> Active(anon): 8256 kB > >> Inactive(anon): 7616 kB > >> > >> First kernel is booted with mem=2G crashkernel=1G command line option. > >> While the system has 64G memory. > >> > >> root at arm64:/home/ubuntu/CODE/crash# cat /proc/iomem > >> 41400000-fffeffff : System RAM > >> 41480000-420cffff : Kernel code > >> 42490000-4278ffff : Kernel data > >> ffff0000-ffffffff : reserved > >> 100000000-ffaa7ffff : System RAM > >> ffaa80000-ffaabffff : reserved > >> ffaac0000-fffa6ffff : System RAM > >> fffa70000-fffacffff : reserved > >> fffad0000-fffffffff : System RAM > > > > Are you saying that "mem=..." doesn't have any effect? > What I am saying it that If the first kernel is booted using mem= option and crashkernel= option > the memory for second kernel has to be withing the crashkernel size. Please don't try to use mem= to limit the kernel to a specific range of memory. It's really only there as a tool to test handling of low-memory situations. While it guarantees that at most, the amount requested will be used (modulo a number of edge cases with reserved memory ranges), it does not guarantee *which* memory will be used. It is *very* fragile. Thanks, Mark.