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s390/zcore: remove /sys/kernel/debug/zcore/mem
New versions of the SCSI dumper use the /dev/vmcore interface instead of zcore mem. Remove the outdated interface. Acked-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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@@ -15,19 +15,15 @@ the s390-tools package) to make the device bootable. The operator of a Linux
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system can then trigger a SCSI dump by booting the SCSI disk, where zfcpdump
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resides on.
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The kernel part of zfcpdump is implemented as a debugfs file under "zcore/mem",
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which exports memory and registers of the crashed Linux in an s390
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standalone dump format. It can be used in the same way as e.g. /dev/mem. The
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dump format defines a 4K header followed by plain uncompressed memory. The
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register sets are stored in the prefix pages of the respective CPUs. To build a
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dump enabled kernel with the zcore driver, the kernel config option
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CONFIG_CRASH_DUMP has to be set. When reading from "zcore/mem", the part of
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memory, which has been saved by hardware is read by the driver via the SCLP
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hardware interface. The second part is just copied from the non overwritten real
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memory.
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The user space dump tool accesses the memory of the crashed system by means
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of the /proc/vmcore interface. This interface exports the crashed system's
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memory and registers in ELF core dump format. To access the memory which has
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been saved by the hardware SCLP requests will be created at the time the data
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is needed by /proc/vmcore. The tail part of the crashed systems memory which
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has not been stashed by hardware can just be copied from real memory.
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Since kernel version 3.12 also the /proc/vmcore file can also be used to access
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the dump.
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To build a dump enabled kernel the kernel config option CONFIG_CRASH_DUMP
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has to be set.
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To get a valid zfcpdump kernel configuration use "make zfcpdump_defconfig".
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