From: Dave Young on
gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/1023#note_5540...
Hi David,
Ok, I had a discussion in kdump team, for X86 since we have
crashkernel=,high and we can reserve more in high memory region so the
risk is low. The only case is what you mentioned if someone allocate
cma=2G then kdump resrevation may fail if the system ram is small. As
the default CMA_SIZE_MBYTES is 0 we should be fine to the change.
As for kdump kernel, we can pass cma=0 in userspace via 2nd kernel
cmdline param, can cma=0 override the behavior in ppc64/s390 as you
mentioned?