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-rw-r--r--Documentation/kdump/kdump.txt28
1 files changed, 17 insertions, 11 deletions
diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index b0f412e42791..7ff213f4becd 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -66,12 +66,18 @@ SETUP
66 CONFIG_PHYSICAL_START=0x1000000 66 CONFIG_PHYSICAL_START=0x1000000
67 c) Enable "/proc/vmcore support" (Optional, in Pseudo filesystems). 67 c) Enable "/proc/vmcore support" (Optional, in Pseudo filesystems).
68 CONFIG_PROC_VMCORE=y 68 CONFIG_PROC_VMCORE=y
69 69 d) Disable SMP support and build a UP kernel (Until it is fixed).
70 Note: Options a) and b) depend upon "Configure standard kernel features 70 CONFIG_SMP=n
71 (for small systems)" (under General setup). 71 e) Enable "Local APIC support on uniprocessors".
72 Option a) also depends on CONFIG_HIGHMEM (under Processor 72 CONFIG_X86_UP_APIC=y
73 f) Enable "IO-APIC support on uniprocessors"
74 CONFIG_X86_UP_IOAPIC=y
75
76 Note: i) Options a) and b) depend upon "Configure standard kernel features
77 (for small systems)" (under General setup).
78 ii) Option a) also depends on CONFIG_HIGHMEM (under Processor
73 type and features). 79 type and features).
74 Both option a) and b) are under "Processor type and features". 80 iii) Both option a) and b) are under "Processor type and features".
75 81
763) Boot into the first kernel. You are now ready to try out kexec-based crash 823) Boot into the first kernel. You are now ready to try out kexec-based crash
77 dumps. 83 dumps.
@@ -79,7 +85,7 @@ SETUP
794) Load the second kernel to be booted using: 854) Load the second kernel to be booted using:
80 86
81 kexec -p <second-kernel> --crash-dump --args-linux --append="root=<root-dev> 87 kexec -p <second-kernel> --crash-dump --args-linux --append="root=<root-dev>
82 maxcpus=1 init 1" 88 init 1 irqpoll"
83 89
84 Note: i) <second-kernel> has to be a vmlinux image. bzImage will not work, 90 Note: i) <second-kernel> has to be a vmlinux image. bzImage will not work,
85 as of now. 91 as of now.
@@ -87,12 +93,12 @@ SETUP
87 is sufficient to represent the physical memory up to 4GB. To store 93 is sufficient to represent the physical memory up to 4GB. To store
88 headers in ELF64 format, specifiy "--elf64-core-headers" on the 94 headers in ELF64 format, specifiy "--elf64-core-headers" on the
89 kexec command line additionally. 95 kexec command line additionally.
90 iii) For now (or until it is fixed), it's best to build the 96 iii) Specify "irqpoll" as command line parameter. This reduces driver
91 second-kernel without multi-processor support, i.e., make it 97 initialization failures in second kernel due to shared interrupts.
92 a uniprocessor kernel.
93 98
945) System reboots into the second kernel when a panic occurs. A module can be 995) System reboots into the second kernel when a panic occurs. A module can be
95 written to force the panic, for testing purposes. 100 written to force the panic or "ALT-SysRq-c" can be used initiate a crash
101 dump for testing purposes.
96 102
976) Write out the dump file using 1036) Write out the dump file using
98 104
@@ -131,5 +137,5 @@ TODO
131CONTACT 137CONTACT
132======= 138=======
133 139
134Hariprasad Nellitheertha - hari at in dot ibm dot com
135Vivek Goyal (vgoyal@in.ibm.com) 140Vivek Goyal (vgoyal@in.ibm.com)
141Maneesh Soni (maneesh@in.ibm.com)