Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758831Ab3EWS5J (ORCPT ); Thu, 23 May 2013 14:57:09 -0400 Received: from e06smtp15.uk.ibm.com ([195.75.94.111]:45288 "EHLO e06smtp15.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758494Ab3EWS5G (ORCPT ); Thu, 23 May 2013 14:57:06 -0400 From: Michael Holzheu To: Vivek Goyal Cc: Jan Willeke , Martin Schwidefsky , Heiko Carstens , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, Michael Holzheu Subject: [PATCH 0/3] kdump: Allow ELF header creation in new kernel Date: Thu, 23 May 2013 20:56:58 +0200 Message-Id: <1369335421-43058-1-git-send-email-holzheu@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.6 X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13052318-0342-0000-0000-0000051E6CCE Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2996 Lines: 80 Hello Vivek, Here, as discussed, the 3nd version of the patch set. ChangeLog ========= v2 => v3) - Get rid of ELFCORE_ADDR_NEWMEM - Make read_from_crash_header() only read from kernel - Move read_from_crash_header() to weak function arch_read_from_crash_header() - Implement read_from_crash_header() strong function for s390 - Set elfcorehdr_addr to address of new ELF header v1 => v2) - Rebase 3.10-rc2 + vmcore mmap patches - Introduced arch_get/free_crash_header() and ELFCORE_ADDR_NEWMEM Feature Description =================== For s390 we want to use /proc/vmcore for our SCSI stand-alone dump (zfcpdump). We have support where the first HSA_SIZE bytes are saved into a hypervisor owned memory area (HSA) before the kdump kernel is booted. When the kdump kernel starts, it is restricted to use only HSA_SIZE bytes. The advantages of this mechanism are: * No crashkernel memory has to be defined in the old kernel. * Early boot problems (before kexec_load has been done) can be dumped * Non-Linux systems can be dumped. We modify the s390 copy_oldmem_page() function to read from the HSA memory if memory below HSA_SIZE bytes is requested. Since we cannot use the kexec tool to load the kernel in this scenario, we have to build the ELF header in the 2nd (kdump/new) kernel. So with the following patch set we would like to introduce the new function that the ELF header for /proc/vmcore can be created in the 2nd kernel memory. The following steps are done during zfcpdump execution: 1. Production system crashes 2. User boots a SCSI disk that has been prepared with the zfcpdump tool 3. Hypervisor saves CPU state of boot CPU and HSA_SIZE bytes of memory into HSA 4. Boot loader loads kernel into low memory area 5. Kernel boots and uses only HSA_SIZE bytes of memory 6. Kernel saves registers of non-boot CPUs 7. Kernel does memory detection for dump memory map 8. Kernel creates ELF header for /proc/vmcore 9. /proc/vmcore uses this header for initialization 10. The zfcpdump user space reads /proc/vmcore to write dump to SCSI disk - copy_oldmem_page() copies from HSA for memory below HSA_SIZE - copy_oldmem_page() copies from real memory for memory above HSA_SIZE Jan Willeke (1): s390/kdump: Use vmcore for zfcpdump Michael Holzheu (2): kdump: Introduce ELF header in new memory feature s390/kdump: Use ELF header in new memory feature arch/s390/Kconfig | 3 +- arch/s390/include/asm/sclp.h | 1 + arch/s390/kernel/crash_dump.c | 138 +++++++++++++++++++++++++++++++----------- drivers/s390/char/zcore.c | 6 +- fs/proc/vmcore.c | 65 ++++++++++++++------ include/linux/crash_dump.h | 4 ++ 6 files changed, 161 insertions(+), 56 deletions(-) -- 1.8.1.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/