[4/4] kdump, documentation: describe craskernel CMA reservation
Commit Message
Describe the new crashkernel ",cma" suffix in Documentation/
---
Documentation/admin-guide/kdump/kdump.rst | 10 ++++++++++
Documentation/admin-guide/kernel-parameters.txt | 7 +++++++
2 files changed, 17 insertions(+)
@@ -317,6 +317,16 @@ crashkernel syntax
crashkernel=0,low
+4) crashkernel=size,cma
+
+ Reserves additional memory from CMA. A standard crashkernel reservation, as
+ described above, is still needed, but can be just small enough to hold the
+ kernel and initrd. All the memory the crash kernel needs for its runtime and
+ for running the kdump userspace processes can be provided by this CMA
+ reservation, re-using memory available to the production system's userspace.
+ Because of this re-using, the CMA reservation should not be used if it's
+ intended to dump userspce memory.
+
Boot into System Kernel
-----------------------
1) Update the boot loader (such as grub, yaboot, or lilo) configuration
@@ -914,6 +914,13 @@
0: to disable low allocation.
It will be ignored when crashkernel=X,high is not used
or memory reserved is below 4G.
+ crashkernel=size[KMG],cma
+ [KNL, X86] Reserve additional crash kernel memory from CMA.
+ This reservation is usable by the 1st system's userspace,
+ so this should not be used if dumping of userspace
+ memory is intended. A standard crashkernel reservation,
+ as described above, is still needed to hold the crash
+ kernel and initrd.
cryptomgr.notests
[KNL] Disable crypto self-tests