[PATCH] kdump documentation update to introduce use of irqpoll
o Specify "irqpoll" command line option which loading second kernel. This
helps in reducing driver initialization failures in second kernel due
to shared interrupts.
o Enabled LAPIC/IOAPIC support for UP kernels in second kernel. This reduces
the chances of devices sharing the irq and hence reduces the chances of
driver initialization failures in second kernel.
o Build a UP capture kernel and disabled SMP support.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index b0f412e..7ff213f 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -66,12 +66,18 @@
CONFIG_PHYSICAL_START=0x1000000
c) Enable "/proc/vmcore support" (Optional, in Pseudo filesystems).
CONFIG_PROC_VMCORE=y
+ d) Disable SMP support and build a UP kernel (Until it is fixed).
+ CONFIG_SMP=n
+ e) Enable "Local APIC support on uniprocessors".
+ CONFIG_X86_UP_APIC=y
+ f) Enable "IO-APIC support on uniprocessors"
+ CONFIG_X86_UP_IOAPIC=y
- Note: Options a) and b) depend upon "Configure standard kernel features
- (for small systems)" (under General setup).
- Option a) also depends on CONFIG_HIGHMEM (under Processor
+ Note: i) Options a) and b) depend upon "Configure standard kernel features
+ (for small systems)" (under General setup).
+ ii) Option a) also depends on CONFIG_HIGHMEM (under Processor
type and features).
- Both option a) and b) are under "Processor type and features".
+ iii) Both option a) and b) are under "Processor type and features".
3) Boot into the first kernel. You are now ready to try out kexec-based crash
dumps.
@@ -79,7 +85,7 @@
4) Load the second kernel to be booted using:
kexec -p <second-kernel> --crash-dump --args-linux --append="root=<root-dev>
- maxcpus=1 init 1"
+ init 1 irqpoll"
Note: i) <second-kernel> has to be a vmlinux image. bzImage will not work,
as of now.
@@ -87,12 +93,12 @@
is sufficient to represent the physical memory up to 4GB. To store
headers in ELF64 format, specifiy "--elf64-core-headers" on the
kexec command line additionally.
- iii) For now (or until it is fixed), it's best to build the
- second-kernel without multi-processor support, i.e., make it
- a uniprocessor kernel.
+ iii) Specify "irqpoll" as command line parameter. This reduces driver
+ initialization failures in second kernel due to shared interrupts.
5) System reboots into the second kernel when a panic occurs. A module can be
- written to force the panic, for testing purposes.
+ written to force the panic or "ALT-SysRq-c" can be used initiate a crash
+ dump for testing purposes.
6) Write out the dump file using
@@ -131,5 +137,5 @@
CONTACT
=======
-Hariprasad Nellitheertha - hari at in dot ibm dot com
Vivek Goyal (vgoyal@in.ibm.com)
+Maneesh Soni (maneesh@in.ibm.com)