Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) ==================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) The s390 SCSI dump tool (zfcpdump)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) ==================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) System z machines (z900 or higher) provide hardware support for creating system
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) dumps on SCSI disks. The dump process is initiated by booting a dump tool, which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) has to create a dump of the current (probably crashed) Linux image. In order to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) not overwrite memory of the crashed Linux with data of the dump tool, the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) hardware saves some memory plus the register sets of the boot CPU before the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) dump tool is loaded. There exists an SCLP hardware interface to obtain the saved
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) memory afterwards. Currently 32 MB are saved.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) This zfcpdump implementation consists of a Linux dump kernel together with
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) a user space dump tool, which are loaded together into the saved memory region
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) below 32 MB. zfcpdump is installed on a SCSI disk using zipl (as contained in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) the s390-tools package) to make the device bootable. The operator of a Linux
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) system can then trigger a SCSI dump by booting the SCSI disk, where zfcpdump
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) resides on.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) The user space dump tool accesses the memory of the crashed system by means
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) of the /proc/vmcore interface. This interface exports the crashed system's
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) memory and registers in ELF core dump format. To access the memory which has
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) been saved by the hardware SCLP requests will be created at the time the data
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) is needed by /proc/vmcore. The tail part of the crashed systems memory which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) has not been stashed by hardware can just be copied from real memory.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) To build a dump enabled kernel the kernel config option CONFIG_CRASH_DUMP
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) has to be set.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) To get a valid zfcpdump kernel configuration use "make zfcpdump_defconfig".
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) The s390 zipl tool looks for the zfcpdump kernel and optional initrd/initramfs
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) under the following locations:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) * kernel:  <zfcpdump directory>/zfcpdump.image
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) * ramdisk: <zfcpdump directory>/zfcpdump.rd
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) The zfcpdump directory is defined in the s390-tools package.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) The user space application of zfcpdump can reside in an intitramfs or an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) initrd. It can also be included in a built-in kernel initramfs. The application
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) reads from /proc/vmcore or zcore/mem and writes the system dump to a SCSI disk.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) The s390-tools package version 1.24.0 and above builds an external zfcpdump
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) initramfs with a user space application that writes the dump to a SCSI
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) partition.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) For more information on how to use zfcpdump refer to the s390 'Using the Dump
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) Tools' book, which is available from IBM Knowledge Center:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) https://www.ibm.com/support/knowledgecenter/linuxonibm/liaaf/lnz_r_dt.html