From: takahiro.akashi@linaro.org (AKASHI Takahiro)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 16/19] arm64: kdump: add kdump support
Date: Fri, 22 Jan 2016 13:50:34 +0900 [thread overview]
Message-ID: <56A1B51A.3000001@linaro.org> (raw)
In-Reply-To: <56A0E869.1020906@arm.com>
James,
On 01/21/2016 11:17 PM, James Morse wrote:
> Hi!
>
> On 15/01/16 19:18, Geoff Levand wrote:
>> From: AKASHI Takahiro <takahiro.akashi@linaro.org>
>>
>> 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.
>>
>> We also need our own elfcorehdr_read() here since the weak definition of
>> elfcorehdr_read() utilizes copy_oldmem_page() and will hit the assertion
>> above on arm64.
>
> How does this work for a different-endian crash kernel?
>
> It looks like fs/proc/vmcore.c:parse_crash_elf64_headers() does some
> validation on the elf-headers that doesn't look like it will work if
> elfcorehdr:endian != kernel:endian.
Good point!
> Is it worth preventing this corner case by getting kexec-tools to
> prevent linux with a different endianness being loaded as a kdump kernel?
It may be, but I think that people should always check whether or not kdump
will work in their environment before puting the system in practical use.
(I know the check costs almost nothing though.)
Thanks,
-Takahiro AKASHI
>
> Thanks,
>
> James
>
>
next prev parent reply other threads:[~2016-01-22 4:50 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-15 19:18 [PATCH 00/19] arm64 kexec kernel patches v13 Geoff Levand
2016-01-15 19:18 ` [PATCH 01/19] arm64: Fold proc-macros.S into assembler.h Geoff Levand
2016-01-15 19:18 ` [PATCH 08/19] Revert "arm64: mm: remove unused cpu_set_idmap_tcr_t0sz function" Geoff Levand
2016-01-15 19:18 ` [PATCH 02/19] arm64: kernel: Include _AC definition in page.h Geoff Levand
2016-01-18 10:05 ` Mark Rutland
2016-01-15 19:18 ` [PATCH 05/19] arm64: Convert hcalls to use HVC immediate value Geoff Levand
2016-01-15 19:18 ` [PATCH 06/19] arm64: Add new hcall HVC_CALL_FUNC Geoff Levand
2016-01-15 19:18 ` [PATCH 09/19] Revert "arm64: remove dead code" Geoff Levand
2016-01-15 19:55 ` Mark Rutland
2016-01-20 21:18 ` Geoff Levand
2016-01-15 19:18 ` [PATCH 03/19] arm64: Add new asm macro copy_page Geoff Levand
2016-01-20 14:01 ` James Morse
2016-01-15 19:18 ` [PATCH 04/19] arm64: Cleanup SCTLR flags Geoff Levand
2016-01-15 20:07 ` Mark Rutland
2016-01-18 10:12 ` Marc Zyngier
2016-01-19 11:59 ` Dave Martin
2016-01-25 15:09 ` James Morse
2016-01-15 19:18 ` [PATCH 07/19] arm64: Add back cpu_reset routines Geoff Levand
2016-01-15 19:18 ` [PATCH 12/19] arm64/kexec: Enable kexec in the arm64 defconfig Geoff Levand
2016-01-15 19:18 ` [PATCH 17/19] arm64: kdump: enable kdump " Geoff Levand
2016-01-15 19:18 ` [PATCH 18/19] arm64: kdump: update a kernel doc Geoff Levand
2016-01-15 20:16 ` Mark Rutland
2016-01-18 10:26 ` AKASHI Takahiro
2016-01-18 11:29 ` Mark Rutland
2016-01-19 5:31 ` AKASHI Takahiro
2016-01-19 12:10 ` Mark Rutland
2016-01-20 4:34 ` AKASHI Takahiro
2016-01-19 1:43 ` Dave Young
2016-01-19 1:50 ` Dave Young
2016-01-19 5:35 ` AKASHI Takahiro
2016-01-19 12:28 ` Dave Young
2016-01-19 12:51 ` Mark Rutland
2016-01-19 13:45 ` Dave Young
2016-01-19 14:01 ` Mark Rutland
2016-01-20 2:49 ` Dave Young
2016-01-20 6:07 ` AKASHI Takahiro
2016-01-20 6:38 ` Dave Young
2016-01-20 7:00 ` Dave Young
2016-01-20 8:01 ` AKASHI Takahiro
2016-01-20 8:26 ` Dave Young
2016-01-20 11:54 ` Mark Rutland
2016-01-21 2:57 ` Dave Young
2016-01-21 3:03 ` Dave Young
2016-01-20 11:49 ` Mark Rutland
2016-01-21 6:53 ` AKASHI Takahiro
2016-01-21 12:02 ` Mark Rutland
2016-01-22 6:23 ` AKASHI Takahiro
2016-01-22 11:13 ` Mark Rutland
2016-02-02 5:18 ` AKASHI Takahiro
2016-01-25 3:19 ` Dave Young
2016-01-25 4:23 ` Dave Young
2016-01-20 11:28 ` Mark Rutland
2016-01-21 2:54 ` Dave Young
2016-01-20 5:25 ` AKASHI Takahiro
2016-01-20 12:02 ` Mark Rutland
2016-01-20 12:36 ` Mark Rutland
2016-01-20 14:59 ` Ard Biesheuvel
2016-01-20 15:04 ` Mark Rutland
2016-01-21 5:43 ` AKASHI Takahiro
2016-01-21 13:02 ` Mark Rutland
2016-01-19 12:17 ` Mark Rutland
2016-01-19 13:52 ` Dave Young
2016-01-19 14:05 ` Mark Rutland
2016-01-20 2:54 ` Dave Young
2016-01-15 19:18 ` [PATCH 11/19] arm64/kexec: Add core kexec support Geoff Levand
2016-01-15 19:18 ` [PATCH 13/19] arm64/kexec: Add pr_debug output Geoff Levand
2016-01-15 19:18 ` [PATCH 16/19] arm64: kdump: add kdump support Geoff Levand
2016-01-21 14:17 ` James Morse
2016-01-22 4:50 ` AKASHI Takahiro [this message]
2016-01-15 19:18 ` [PATCH 10/19] arm64: kvm: allows kvm cpu hotplug Geoff Levand
2016-01-26 17:42 ` James Morse
2016-01-27 7:37 ` AKASHI Takahiro
2016-01-15 19:18 ` [PATCH 19/19] arm64: kdump: relax BUG_ON() if more than one cpus are still active Geoff Levand
2016-01-15 19:18 ` [PATCH 15/19] arm64: kdump: implement machine_crash_shutdown() Geoff Levand
2016-01-15 19:18 ` [PATCH 14/19] arm64: kdump: reserve memory for crash dump kernel Geoff Levand
2016-01-19 12:32 ` [PATCH 00/19] arm64 kexec kernel patches v13 Dave Young
2016-01-20 0:15 ` Geoff Levand
2016-01-20 2:56 ` Dave Young
2016-01-20 21:15 ` Geoff Levand
2016-01-21 12:11 ` Mark Rutland
[not found] ` <c7575f853ccc491bb0212e025aab1cc9@NASANEXM01H.na.qualcomm.com>
2016-03-01 17:54 ` Azriel Samson
2016-03-02 1:17 ` Geoff Levand
2016-03-02 1:38 ` Will Deacon
2016-03-02 2:28 ` AKASHI Takahiro
2016-03-02 8:07 ` Marc Zyngier
2016-03-02 12:33 ` Pratyush Anand
2016-03-02 16:51 ` Azriel Samson
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