From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752805AbbEKH7C (ORCPT ); Mon, 11 May 2015 03:59:02 -0400 Received: from mail-pa0-f50.google.com ([209.85.220.50]:36587 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751870AbbEKH66 (ORCPT ); Mon, 11 May 2015 03:58:58 -0400 Message-ID: <5550613A.3070506@linaro.org> Date: Mon, 11 May 2015 16:58:50 +0900 From: AKASHI Takahiro User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Dave Young CC: linux-arm-kernel@lists.infradead.org, hbabus@us.ibm.com, linaro-kernel@lists.linaro.org, geoff@infradead.org, catalin.marinas@arm.com, panand@redhat.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, broonie@kernel.org, david.griego@linaro.org, kexec@lists.infradead.org, vgoyal@redhat.com Subject: Re: [v2 4/5] arm64: add kdump support References: <1429861989-8417-1-git-send-email-takahiro.akashi@linaro.org> <1429861989-8417-5-git-send-email-takahiro.akashi@linaro.org> <20150508121921.GA18400@localhost.localdomain> <20150511074728.GA15884@dhcp-128-124.nay.redhat.com> In-Reply-To: <20150511074728.GA15884@dhcp-128-124.nay.redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dave, On 05/11/2015 04:47 PM, Dave Young wrote: > On 05/08/15 at 08:19pm, Dave Young wrote: >> Hi, >> >> On 04/24/15 at 04:53pm, AKASHI Takahiro wrote: >>> Please read the following commits for arm64-specific constraints: >>> arm64: kdump: reserve memory for crash dump kernel >>> arm64: kdump: do not go into EL2 before starting a crash dump kernel >>> >>> Signed-off-by: AKASHI Takahiro >>> --- >>> Documentation/kdump/kdump.txt | 31 ++++++++++++++++++++++++++++++- >>> arch/arm64/Kconfig | 12 ++++++++++++ >>> 2 files changed, 42 insertions(+), 1 deletion(-) >>> >>> diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt >>> index bc4bd5a..f9cf6f5 100644 >>> --- a/Documentation/kdump/kdump.txt >>> +++ b/Documentation/kdump/kdump.txt >>> @@ -18,7 +18,7 @@ memory image to a dump file on the local disk, or across the network to >>> a remote system. >>> >>> Kdump and kexec are currently supported on the x86, x86_64, ppc64, ia64, >>> -s390x and arm architectures. >>> +s390x, arm and arm64 architectures. >>> >>> When the system kernel boots, it reserves a small section of memory for >>> the dump-capture kernel. This ensures that ongoing Direct Memory Access >>> @@ -249,6 +249,29 @@ Dump-capture kernel config options (Arch Dependent, arm) >>> >>> AUTO_ZRELADDR=y >>> >>> +Dump-capture kernel config options (Arch Dependent, arm64) >>> +---------------------------------------------------------- >>> + >>> +1) Disable symmetric multi-processing support under "Processor type and >>> + features": >>> + >>> + CONFIG_SMP=n >>> + >>> + (If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line >>> + when loading the dump-capture kernel, see section "Load the Dump-capture >>> + Kernel".) >>> + >>> +2) Under uefi, the maximum memory size on the dump-capture kernel must be >>> + limited by specifying: >>> + >>> + mem=X[MG] >>> + >>> + where X should be less than or equal to the size in "crashkernel=" >>> + boot parameter. Kexec-tools will automatically add this. >> >> I noticed you are passing mem=X in kexec-tools, Pratyush found a problem >> that vmcore is corrupted because kdump kernel is using the crash notes memory. >> >> How does kdump kernel know the system ram range especially the mem_start? >> Only with the size from mem=? parammeter? >> >> In X86 because it use E820 so kexec-tools can pass the memory range to kdump >> kernel even for UEFI booting. But in arm64 may need find other way to >> communicate with 2nd kernel like memmap=exactmap in X86.. > > Discussed with Pratyush in irc, he mentioned that start address is get from > kernel->entry which was passed by kexec-tools. > > So sorry for the noise, it will works fine with the UEFI mem= limitation > fix from Mark Salter No, not at all. As you know, in another thread (with Mark), we're discussing this. If we conclude that we should go for "memmap=" approach, I will update my patch. Thanks, -Takahiro AKASHI >> >>> + >>> +3) Currently, kvm will not be initialized on the dump-capture kernel even >>> + if it is configured. >>> + >>> Extended crashkernel syntax >>> =========================== >>> >>> @@ -312,6 +335,7 @@ Boot into System Kernel >>> any space below the alignment point may be overwritten by the dump-capture kernel, >>> which means it is possible that the vmcore is not that precise as expected. >>> >>> + On arm64, use "crashkernel=Y@X". >>> >>> Load the Dump-capture Kernel >>> ============================ >>> @@ -334,6 +358,8 @@ For s390x: >>> - Use image or bzImage >>> For arm: >>> - Use zImage >>> +For arm64: >>> + - Use vmlinux >>> >>> If you are using a uncompressed vmlinux image then use following command >>> to load dump-capture kernel. >>> @@ -377,6 +403,9 @@ For s390x: >>> For arm: >>> "1 maxcpus=1 reset_devices" >>> >>> +For arm64: >>> + "1 maxcpus=1 mem=X[MG] reset_devices" >>> + >>> Notes on loading the dump-capture kernel: >>> >>> * By default, the ELF headers are stored in ELF64 format to support >>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >>> index 5716edf..8e2f545 100644 >>> --- a/arch/arm64/Kconfig >>> +++ b/arch/arm64/Kconfig >>> @@ -562,6 +562,18 @@ config KEXEC >>> but it is independent of the system firmware. And like a reboot >>> you can start any kernel with it, not just Linux. >>> >>> +config CRASH_DUMP >>> + bool "Build kdump crash kernel" >>> + help >>> + Generate crash dump after being started by kexec. This should >>> + be normally only set in special crash dump kernels which are >>> + loaded in the main kernel with kexec-tools into a specially >>> + reserved region and then later executed after a crash by >>> + kdump/kexec. The crash dump kernel must be compiled to a >>> + memory address not used by the main kernel. >>> + >>> + For more details see Documentation/kdump/kdump.txt >>> + >>> config XEN_DOM0 >>> def_bool y >>> depends on XEN >>> -- >>> 1.7.9.5 >>> >>> >>> _______________________________________________ >>> kexec mailing list >>> kexec@lists.infradead.org >>> http://lists.infradead.org/mailman/listinfo/kexec >>> >>> >> >> _______________________________________________ >> kexec mailing list >> kexec@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/kexec >> >>