Commit d58831e4 authored by Vivek Goyal's avatar Vivek Goyal Committed by Linus Torvalds
Browse files

[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: default avatarVivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent b089f4a6

Documentation/kdump/kdump.txt

+17 −11
Original line number Diff line number Diff line
@@ -66,12 +66,18 @@ SETUP 
	CONFIG_PHYSICAL_START=0x1000000

   c) Enable "/proc/vmcore support" (Optional, in Pseudo filesystems).

	CONFIG_PROC_VMCORE=y



  Note: Options a) and b) depend upon "Configure standard kernel features

   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:   i) 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

	 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 @@ SETUP 
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 @@ SETUP 
	    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 @@ TODO 
CONTACT

=======



Hariprasad Nellitheertha - hari at in dot ibm dot com

Vivek Goyal (vgoyal@in.ibm.com)

Maneesh Soni (maneesh@in.ibm.com)

CRA Git | Maintained and supported by SUSTech CRA and CCSE