From 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 Mon Sep 17 00:00:00 2001 From: Yunhong Jiang Date: Tue, 4 Aug 2015 12:17:53 -0700 Subject: Add the rt linux 4.1.3-rt3 as base Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang --- kernel/Documentation/s390/zfcpdump.txt | 52 ++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 kernel/Documentation/s390/zfcpdump.txt (limited to 'kernel/Documentation/s390/zfcpdump.txt') diff --git a/kernel/Documentation/s390/zfcpdump.txt b/kernel/Documentation/s390/zfcpdump.txt new file mode 100644 index 000000000..dc929be96 --- /dev/null +++ b/kernel/Documentation/s390/zfcpdump.txt @@ -0,0 +1,52 @@ +The s390 SCSI dump tool (zfcpdump) + +System z machines (z900 or higher) provide hardware support for creating system +dumps on SCSI disks. The dump process is initiated by booting a dump tool, which +has to create a dump of the current (probably crashed) Linux image. In order to +not overwrite memory of the crashed Linux with data of the dump tool, the +hardware saves some memory plus the register sets of the boot CPU before the +dump tool is loaded. There exists an SCLP hardware interface to obtain the saved +memory afterwards. Currently 32 MB are saved. + +This zfcpdump implementation consists of a Linux dump kernel together with +a user space dump tool, which are loaded together into the saved memory region +below 32 MB. zfcpdump is installed on a SCSI disk using zipl (as contained in +the s390-tools package) to make the device bootable. The operator of a Linux +system can then trigger a SCSI dump by booting the SCSI disk, where zfcpdump +resides on. + +The kernel part of zfcpdump is implemented as a debugfs file under "zcore/mem", +which exports memory and registers of the crashed Linux in an s390 +standalone dump format. It can be used in the same way as e.g. /dev/mem. The +dump format defines a 4K header followed by plain uncompressed memory. The +register sets are stored in the prefix pages of the respective CPUs. To build a +dump enabled kernel with the zcore driver, the kernel config option +CONFIG_CRASH_DUMP has to be set. When reading from "zcore/mem", the part of +memory, which has been saved by hardware is read by the driver via the SCLP +hardware interface. The second part is just copied from the non overwritten real +memory. + +Since kernel version 3.12 also the /proc/vmcore file can also be used to access +the dump. + +To get a valid zfcpdump kernel configuration use "make zfcpdump_defconfig". + +The s390 zipl tool looks for the zfcpdump kernel and optional initrd/initramfs +under the following locations: + +* kernel: /zfcpdump.image +* ramdisk: /zfcpdump.rd + +The zfcpdump directory is defined in the s390-tools package. + +The user space application of zfcpdump can reside in an intitramfs or an +initrd. It can also be included in a built-in kernel initramfs. The application +reads from /proc/vmcore or zcore/mem and writes the system dump to a SCSI disk. + +The s390-tools package version 1.24.0 and above builds an external zfcpdump +initramfs with a user space application that writes the dump to a SCSI +partition. + +For more information on how to use zfcpdump refer to the s390 'Using the Dump +Tools book', which is available from +http://www.ibm.com/developerworks/linux/linux390. -- cgit 1.2.3-korg