From: Bernhard Walle This adds the documentation for the extended crashkernel syntax into Documentation/kdump/kdump.txt. Signed-off-by: Bernhard Walle Cc: Andi Kleen Cc: "Luck, Tony" Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Paul Mundt Cc: Vivek Goyal Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton --- Documentation/kdump/kdump.txt | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff -puN Documentation/kdump/kdump.txt~add-documentation-for-extended-crashkernel-syntax Documentation/kdump/kdump.txt --- a/Documentation/kdump/kdump.txt~add-documentation-for-extended-crashkernel-syntax +++ a/Documentation/kdump/kdump.txt @@ -231,6 +231,32 @@ Dump-capture kernel config options (Arch any space below the alignment point will be wasted. +Extended crashkernel syntax +=========================== + +While the "crashkernel=size[@offset]" syntax is sufficient for most +configurations, sometimes it's handy to have the reserved memory dependent +on the value of System RAM -- that's mostly for distributors that pre-setup +the kernel command line to avoid a unbootable system after some memory has +been removed from the machine. + +The syntax is: + + crashkernel=:[,:,...][@offset] + range=start-[end] + +For example: + + crashkernel=512M-2G:64M,2G-:128M + +This would mean: + + 1) if the RAM is smaller than 512M, then don't reserve anything + (this is the "rescue" case) + 2) if the RAM size is between 512M and 2G, then reserve 64M + 3) if the RAM size is larger than 2G, then reserve 128M + + Boot into System Kernel ======================= _