Re: [PATCH] fadump-howto: update about 'nocma' and 'off' options for 'fadump=' parameter
On 11/25/2020 01:55 PM, Hari Bathini wrote:
Along with 'on' option, 'fadump=' kernel parameter
also supports
'nocma' & 'off' options. Update about these missing options in the
fadump-howto.txt document.
Signed-off-by: Hari Bathini <hbathini(a)linux.ibm.com>
---
fadump-howto.txt | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/fadump-howto.txt b/fadump-howto.txt
index c891e37..5360f3d 100644
--- a/fadump-howto.txt
+++ b/fadump-howto.txt
@@ -104,6 +104,11 @@ For the recommended value of X, see 'FADump Memory
Requirements' section.
# grubby --args="fadump=on crashkernel=6G"
--update-kernel=/boot/vmlinuz-`uname -r`
+By default, FADump reserved memory will be initialized as CMA area to make the
+memory available through CMA allocator on the production kernel. We can opt out
+of this, making reserved memory unavailable to production kernel, by booting the
+linux kernel with 'fadump=nocma' instead of 'fadump=on'.
+
The term 'boot memory' means size of the low memory chunk that is required for
a kernel to boot successfully when booted with restricted memory. By default,
the boot memory size will be the larger of 5% of system RAM or 256MB.
@@ -326,9 +331,14 @@ the original command line completely.
How to disable FADump:
-Remove "fadump=on" from kernel cmdline parameters:
+Remove "fadump=on"/"fadump=nocma" from kernel cmdline parameters OR
replace
+it with "fadump=off" kernel cmdline parameter:
# grubby --update-kernel=/boot/vmlinuz-`uname -r`
--remove-args="fadump=on"
+or
+ # grubby --update-kernel=/boot/vmlinuz-`uname -r`
--remove-args="fadump=nocma"
+OR
+ # grubby --update-kernel=/boot/vmlinuz-`uname -r` --args="fadump=off"
If KDump is to be used as the dump capturing mechanism, update the crashkernel
parameter (Else, remove "crashkernel=" parameter too, using grubby):
Acked-by: Pingfan Liu <piliu(a)redhat.com>