Comment 2 for bug 1570775

------- Comment From <email address hidden> 2016-05-03 07:28 EDT-------
On an LPAR with 8458 (!!) ccw devices (only 11 of them in use) I set crashkernel with various values:
256M : no dump created
288M : oom killer killed some processes, dump was created, but system did not come up
320M : no oom killer, dump properly created
Then I invoked cio_ignore -u -k and added these values to KDUMP_CMD_APPEND in /etc/default/kdump_tools. Kdump worked fine, even with crashkernel=128M

IMO the best thing is to set this dynamically in /etc/default/kdump_tools by the following suggested patch:
--- /etc/default/kdump-tools.orig 2016-04-21 15:11:57.000000000 +0200
+++ /etc/default/kdump-tools 2016-05-03 13:17:38.862816261 +0200
@@ -63,7 +63,8 @@
# for the kdump kernel. If unset, it defaults to "irqpoll maxcpus=1 nousb"
#KDUMP_KEXEC_ARGS=""
#KDUMP_CMDLINE=""
-#KDUMP_CMDLINE_APPEND="irqpoll maxcpus=1 nousb systemd.unit=kdump-tools.service"
+APPEND=
+KDUMP_CMDLINE_APPEND="irqpoll maxcpus=1 nousb systemd.unit=kdump-tools.service $APPEND"

# ---------------------------------------------------------------------------
# Architecture specific Overrides:

The cmdline during kdump is set properly, the values from cio_ignore are reflected.