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-rw-r--r--Documentation/kdump/kdump.txt9
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index 88ff63d5fde3..b0eb27b956d9 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -393,6 +393,15 @@ Notes on loading the dump-capture kernel:
* We generally don' have to bring up a SMP kernel just to capture the
dump. Hence generally it is useful either to build a UP dump-capture
kernel or specify maxcpus=1 option while loading dump-capture kernel.
+ Note, though maxcpus always works, you had better replace it with
+ nr_cpus to save memory if supported by the current ARCH, such as x86.
+
+* You should enable multi-cpu support in dump-capture kernel if you intend
+ to use multi-thread programs with it, such as parallel dump feature of
+ makedumpfile. Otherwise, the multi-thread program may have a great
+ performance degradation. To enable multi-cpu support, you should bring up an
+ SMP dump-capture kernel and specify maxcpus/nr_cpus, disable_cpu_apicid=[X]
+ options while loading it.
* For s390x there are two kdump modes: If a ELF header is specified with
the elfcorehdr= kernel parameter, it is used by the kdump kernel as it