[S390] zfcpdump support. (411ed322) · Commits · e / devices / android_kernel_teracube_emerald

Documentation/s390/zfcpdump.txt

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			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 userspace 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_ZFCPDUMP 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.

			The userspace application of zfcpdump can reside e.g. in an intitramfs or an
			initrd. It reads from zcore/mem and writes the system dump to a file on a
			SCSI disk.

			To build a zfcpdump kernel use the following settings in your kernel
			configuration:
			* CONFIG_ZFCPDUMP=y
			* Enable ZFCP driver
			* Enable SCSI driver
			* Enable ext2 and ext3 filesystems
			* Disable as many features as possible to keep the kernel small.
			E.g. network support is not needed at all.

			To use the zfcpdump userspace application in an initramfs you have to do the
			following:

			* Copy the zfcpdump executable somewhere into your Linux tree.
			E.g. to "arch/s390/boot/zfcpdump. If you do not want to include
			shared libraries, compile the tool with the "-static" gcc option.
			* If you want to include e2fsck, add it to your source tree, too. The zfcpdump
			application attempts to start /sbin/e2fsck from the ramdisk.
			* Use an initramfs config file like the following:

			dir /dev 755 0 0
			nod /dev/console 644 0 0 c 5 1
			nod /dev/null 644 0 0 c 1 3
			nod /dev/sda1 644 0 0 b 8 1
			nod /dev/sda2 644 0 0 b 8 2
			nod /dev/sda3 644 0 0 b 8 3
			nod /dev/sda4 644 0 0 b 8 4
			nod /dev/sda5 644 0 0 b 8 5
			nod /dev/sda6 644 0 0 b 8 6
			nod /dev/sda7 644 0 0 b 8 7
			nod /dev/sda8 644 0 0 b 8 8
			nod /dev/sda9 644 0 0 b 8 9
			nod /dev/sda10 644 0 0 b 8 10
			nod /dev/sda11 644 0 0 b 8 11
			nod /dev/sda12 644 0 0 b 8 12
			nod /dev/sda13 644 0 0 b 8 13
			nod /dev/sda14 644 0 0 b 8 14
			nod /dev/sda15 644 0 0 b 8 15
			file /init arch/s390/boot/zfcpdump 755 0 0
			file /sbin/e2fsck arch/s390/boot/e2fsck 755 0 0
			dir /proc 755 0 0
			dir /sys 755 0 0
			dir /mnt 755 0 0
			dir /sbin 755 0 0

			* Issue "make image" to build the zfcpdump image with initramfs.

			In a Linux distribution the zfcpdump enabled kernel image must be copied to
			/usr/share/zfcpdump/zfcpdump.image, where the s390 zipl tool is looking for the
			dump kernel when preparing a SCSI dump disk.

			If you use a ramdisk copy it to "/usr/share/zfcpdump/zfcpdump.rd".

			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.

arch/s390/Kconfig

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	@@ -519,6 +519,14 @@ config KEXEC
	current kernel, and to start another kernel. It is like a reboot		current kernel, and to start another kernel. It is like a reboot
	but is independent of hardware/microcode support.		but is independent of hardware/microcode support.

			config ZFCPDUMP
			tristate "zfcpdump support"
			select SMP
			default n
			help
			Select this option if you want to build an zfcpdump enabled kernel.
			Refer to "Documentation/s390/zfcpdump.txt" for more details on this.

	endmenu		endmenu

	source "net/Kconfig"		source "net/Kconfig"

arch/s390/Makefile

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	@@ -105,6 +105,9 @@ install: vmlinux
	image: vmlinux		image: vmlinux
	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@		$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@

			zfcpdump:
			$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@

	archclean:		archclean:
	$(Q)$(MAKE) $(clean)=$(boot)		$(Q)$(MAKE) $(clean)=$(boot)

arch/s390/defconfig

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	@@ -167,6 +167,7 @@ CONFIG_NO_IDLE_HZ=y
	CONFIG_NO_IDLE_HZ_INIT=y		CONFIG_NO_IDLE_HZ_INIT=y
	CONFIG_S390_HYPFS_FS=y		CONFIG_S390_HYPFS_FS=y
	CONFIG_KEXEC=y		CONFIG_KEXEC=y
			# CONFIG_ZFCPDUMP is not set

	#		#
	# Networking		# Networking

arch/s390/kernel/head64.S

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	@@ -39,7 +39,69 @@ startup_continue:
	basr %r13,0 # get base		basr %r13,0 # get base
	.LPG1: sll %r13,1 # remove high order bit		.LPG1: sll %r13,1 # remove high order bit
	srl %r13,1		srl %r13,1
	lhi %r1,1 # mode 1 = esame
			#ifdef CONFIG_ZFCPDUMP

			# check if we have been ipled using zfcp dump:

			tm 0xb9,0x01 # test if subchannel is enabled
			jno .nodump # subchannel disabled
			l %r1,0xb8
			la %r5,.Lipl_schib-.LPG1(%r13)
			stsch 0(%r5) # get schib of subchannel
			jne .nodump # schib not available
			tm 5(%r5),0x01 # devno valid?
			jno .nodump
			tm 4(%r5),0x80 # qdio capable device?
			jno .nodump
			l %r2,20(%r0) # address of ipl parameter block
			lhi %r3,0
			ic %r3,0x148(%r2) # get opt field
			chi %r3,0x20 # load with dump?
			jne .nodump

			# store all prefix registers in case of load with dump:

			la %r7,0 # base register for 0 page
			la %r8,0 # first cpu
			l %r11,.Lpref_arr_ptr-.LPG1(%r13) # address of prefix array
			ahi %r11,4 # skip boot cpu
			lr %r12,%r11
			ahi %r12,(CONFIG_NR_CPUS*4) # end of prefix array
			stap .Lcurrent_cpu+2-.LPG1(%r13) # store current cpu addr
			1:
			cl %r8,.Lcurrent_cpu-.LPG1(%r13) # is ipl cpu ?
			je 4f # if yes get next cpu
			2:
			lr %r9,%r7
			sigp %r9,%r8,0x9 # stop & store status of cpu
			brc 8,3f # accepted
			brc 4,4f # status stored: next cpu
			brc 2,2b # busy: try again
			brc 1,4f # not op: next cpu
			3:
			mvc 0(4,%r11),264(%r7) # copy prefix register to prefix array
			ahi %r11,4 # next element in prefix array
			clr %r11,%r12
			je 5f # no more space in prefix array
			4:
			ahi %r8,1 # next cpu (r8 += 1)
			cl %r8,.Llast_cpu-.LPG1(%r13) # is last possible cpu ?
			jl 1b # jump if not last cpu
			5:
			lhi %r1,2 # mode 2 = esame (dump)
			j 6f
			.align 4
			.Lipl_schib:
			.rept 13
			.long 0
			.endr
			.nodump:
			lhi %r1,1 # mode 1 = esame (normal ipl)
			6:
			#else
			lhi %r1,1 # mode 1 = esame (normal ipl)
			#endif /* CONFIG_ZFCPDUMP */
	mvi __LC_AR_MODE_ID,1 # set esame flag		mvi __LC_AR_MODE_ID,1 # set esame flag
	slr %r0,%r0 # set cpuid to zero		slr %r0,%r0 # set cpuid to zero
	sigp %r1,%r0,0x12 # switch to esame mode		sigp %r1,%r0,0x12 # switch to esame mode
	@@ -149,6 +211,14 @@ startup_continue:
	.L4malign:.quad 0xffffffffffc00000		.L4malign:.quad 0xffffffffffc00000
	.Lscan2g:.quad 0x80000000 + 0x20000 - 8 # 2GB + 128K - 8		.Lscan2g:.quad 0x80000000 + 0x20000 - 8 # 2GB + 128K - 8
	.Lnop: .long 0x07000700		.Lnop: .long 0x07000700
			#ifdef CONFIG_ZFCPDUMP
			.Lcurrent_cpu:
			.long 0x0
			.Llast_cpu:
			.long 0x0000ffff
			.Lpref_arr_ptr:
			.long zfcpdump_prefix_array
			#endif /* CONFIG_ZFCPDUMP */
	.Lparmaddr:		.Lparmaddr:
	.quad PARMAREA		.quad PARMAREA
	.align 64		.align 64