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authorMichael Holzheu <holzheu@linux.vnet.ibm.com>2011-12-27 05:27:25 -0500
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2011-12-27 05:27:13 -0500
commit913021433997936822e33a62decfb1914de9bc51 (patch)
tree640201ebb840ed9d88ca4eb50693c93c3f1060d0 /Documentation
parent7fe7a18cddf35f0d50d681ae6252241303b0cfc5 (diff)
[S390] Add s390x description to Documentation/kdump/kdump.txt
Add s390x specific parts to kdump kernel documentation. Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/kdump/kdump.txt35
1 files changed, 32 insertions, 3 deletions
diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index 7a9e0b4b2903..506c7390c2b9 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -17,8 +17,8 @@ You can use common commands, such as cp and scp, to copy the
17memory image to a dump file on the local disk, or across the network to 17memory image to a dump file on the local disk, or across the network to
18a remote system. 18a remote system.
19 19
20Kdump and kexec are currently supported on the x86, x86_64, ppc64 and ia64 20Kdump and kexec are currently supported on the x86, x86_64, ppc64, ia64,
21architectures. 21and s390x architectures.
22 22
23When the system kernel boots, it reserves a small section of memory for 23When the system kernel boots, it reserves a small section of memory for
24the dump-capture kernel. This ensures that ongoing Direct Memory Access 24the dump-capture kernel. This ensures that ongoing Direct Memory Access
@@ -34,11 +34,18 @@ Similarly on PPC64 machines first 32KB of physical memory is needed for
34booting regardless of where the kernel is loaded and to support 64K page 34booting regardless of where the kernel is loaded and to support 64K page
35size kexec backs up the first 64KB memory. 35size kexec backs up the first 64KB memory.
36 36
37For s390x, when kdump is triggered, the crashkernel region is exchanged
38with the region [0, crashkernel region size] and then the kdump kernel
39runs in [0, crashkernel region size]. Therefore no relocatable kernel is
40needed for s390x.
41
37All of the necessary information about the system kernel's core image is 42All of the necessary information about the system kernel's core image is
38encoded in the ELF format, and stored in a reserved area of memory 43encoded in the ELF format, and stored in a reserved area of memory
39before a crash. The physical address of the start of the ELF header is 44before a crash. The physical address of the start of the ELF header is
40passed to the dump-capture kernel through the elfcorehdr= boot 45passed to the dump-capture kernel through the elfcorehdr= boot
41parameter. 46parameter. Optionally the size of the ELF header can also be passed
47when using the elfcorehdr=[size[KMG]@]offset[KMG] syntax.
48
42 49
43With the dump-capture kernel, you can access the memory image, or "old 50With the dump-capture kernel, you can access the memory image, or "old
44memory," in two ways: 51memory," in two ways:
@@ -291,6 +298,10 @@ Boot into System Kernel
291 The region may be automatically placed on ia64, see the 298 The region may be automatically placed on ia64, see the
292 dump-capture kernel config option notes above. 299 dump-capture kernel config option notes above.
293 300
301 On s390x, typically use "crashkernel=xxM". The value of xx is dependent
302 on the memory consumption of the kdump system. In general this is not
303 dependent on the memory size of the production system.
304
294Load the Dump-capture Kernel 305Load the Dump-capture Kernel
295============================ 306============================
296 307
@@ -308,6 +319,8 @@ For ppc64:
308 - Use vmlinux 319 - Use vmlinux
309For ia64: 320For ia64:
310 - Use vmlinux or vmlinuz.gz 321 - Use vmlinux or vmlinuz.gz
322For s390x:
323 - Use image or bzImage
311 324
312 325
313If you are using a uncompressed vmlinux image then use following command 326If you are using a uncompressed vmlinux image then use following command
@@ -337,6 +350,8 @@ For i386, x86_64 and ia64:
337For ppc64: 350For ppc64:
338 "1 maxcpus=1 noirqdistrib reset_devices" 351 "1 maxcpus=1 noirqdistrib reset_devices"
339 352
353For s390x:
354 "1 maxcpus=1 cgroup_disable=memory"
340 355
341Notes on loading the dump-capture kernel: 356Notes on loading the dump-capture kernel:
342 357
@@ -362,6 +377,20 @@ Notes on loading the dump-capture kernel:
362 dump. Hence generally it is useful either to build a UP dump-capture 377 dump. Hence generally it is useful either to build a UP dump-capture
363 kernel or specify maxcpus=1 option while loading dump-capture kernel. 378 kernel or specify maxcpus=1 option while loading dump-capture kernel.
364 379
380* For s390x there are two kdump modes: If a ELF header is specified with
381 the elfcorehdr= kernel parameter, it is used by the kdump kernel as it
382 is done on all other architectures. If no elfcorehdr= kernel parameter is
383 specified, the s390x kdump kernel dynamically creates the header. The
384 second mode has the advantage that for CPU and memory hotplug, kdump has
385 not to be reloaded with kexec_load().
386
387* For s390x systems with many attached devices the "cio_ignore" kernel
388 parameter should be used for the kdump kernel in order to prevent allocation
389 of kernel memory for devices that are not relevant for kdump. The same
390 applies to systems that use SCSI/FCP devices. In that case the
391 "allow_lun_scan" zfcp module parameter should be set to zero before
392 setting FCP devices online.
393
365Kernel Panic 394Kernel Panic
366============ 395============
367 396