kdump-lib: Extend _crashkernel_add() with a param

Currently, crashkernel_add() adjusts each range in the 'crashkernel='
command line by adding a delta value. This adjustment is necessary
because certain hardware features require significant additional memory
(up to 1GB on some ARM64 machines).

While this approach works well for traditional installations, OSTree
deployments present a challenge: kdump cannot detect the hardware
environment on the target platform. One solution is to maximize the
memory reserved for the kdump kernel.  However, while this increased
allocation ensures kdump functionality, it raises the risk of OOM
conditions in the production kernel, particularly on small-memory
machines that typically lack such hardware features (Mellanox network
cards, SMMU, SME).

This patch extends crashkernel_add() with a parameter
to skip the first N ranges in the 'crashkernel=' command line. Later, we
can use it to skip the first range.

Signed-off-by: Pingfan Liu <[email protected]>

Author: Pingfan Liu

kdump-lib.sh

@@ -946,13 +946,16 @@ _crashkernel_parse()
 
 # $1 crashkernel command line parameter
 # $2 size to be added
+# $3 optionally skip the first n items in command line
 _crashkernel_add()
 {
-	local ck delta ret
+	local ck delta skip ret
 	local range size offset
+	local count=0
 
 	ck="$1"
 	delta="$2"
+	skip="${3:-0}" # Default to 0 if third parameter not provided
 	ret=""
 
 	while IFS=';' read -r size range offset; do
@@ -967,8 +970,12 @@ _crashkernel_add()
 			ret+="$range:"
 		fi
 
-		size=$(memsize_add "$size" "$delta") || return 1
+		if ((count >= skip)); then
+			size=$(memsize_add "$size" "$delta") || return 1
+		fi
+
 		ret+="$size,"
+		((count++))
 	done < <(_crashkernel_parse "$ck")
 
 	echo "${ret%,}"