diff --git a/kdumpctl b/kdumpctl
index 113d8bc..6e4685f 100755
--- a/kdumpctl
+++ b/kdumpctl
@@ -1480,69 +1480,9 @@ _get_all_kernels_from_grubby()
 	echo -n "$_kernels"
 }
 
-GRUB_ETC_DEFAULT="/etc/default/grub"
-# Update a kernel parameter in default grub conf
-#
-# If a value is specified, it will be inserted in the end. Otherwise it
-# would remove given kernel parameter.
-#
-# Note this function doesn't address the following cases,
-# 1. The kernel ignores everything on the command line after a '--'. So
-#    simply adding the new entry to the end will fail if the cmdline
-#    contains a --.
-# 2. If the value for a parameter contains spaces it can be quoted using
-#    double quotes, for example param="value with spaces". This will
-#    break the [^[:space:]\"] regex for the value.
-# 3. Dashes and underscores in the parameter name are equivalent. So
-#    some_parameter and some-parameter are identical.
-# 4. Some parameters, e.g. efivar_ssdt, can be given multiple times.
-# 5. Some kernel parameters, e.g. quiet, doesn't have value
-#
-# $1: the name of the kernel command line parameter
-# $2: new value. If empty, given parameter would be removed
-_update_kernel_arg_in_grub_etc_default()
-{
-	local _para=$1 _val=$2 _para_val
-
-	if [[ $(uname -m) == s390x ]]; then
-		return
-	fi
-
-	if [[ -n $_val ]]; then
-		_para_val="$_para=$_val"
-	fi
-
-	# Update the command line /etc/default/grub, i.e.
-	# on the line that starts with 'GRUB_CMDLINE_LINUX=',
-	#       1) remove $para=$val if the it's the first arg
-	#       2) remove all occurences of $para=$val
-	#       3) insert $_para_val to end
-	#       4) remove duplicate spaces left over by 1) or 2) or 3)
-	#       5) remove space at the beginning of the string left over by 1) or 2) or 3)
-	#       6) remove space at the end of the string left over by 1) or 2) or 3)
-	sed -i -E "/^GRUB_CMDLINE_LINUX=/ {
-         s/\"${_para}=[^[:space:]\"]*/\"/g;
-         s/[[:space:]]+${_para}=[^[:space:]\"]*/ /g;
-         s/\"$/ ${_para_val}\"/
-         s/[[:space:]]+/ /g;
-         s/(\")[[:space:]]+/\1/g;
-         s/[[:space:]]+(\")/\1/g;
-         }" "$GRUB_ETC_DEFAULT"
-}
-
-# Read the kernel arg in default grub conf.
-
-# Note reading a kernel parameter that doesn't have a value isn't supported.
-#
-# $1: the name of the kernel command line parameter
-_read_kernel_arg_in_grub_etc_default()
-{
-	sed -n -E "s/^GRUB_CMDLINE_LINUX=.*[[:space:]\"]${1}=([^[:space:]\"]*).*$/\1/p" "$GRUB_ETC_DEFAULT"
-}
-
 reset_crashkernel()
 {
-	local _opt _val _fadump_val _reboot _grubby_kernel_path _kernel _kernels
+	local _opt _val _reboot _grubby_kernel_path _kernel _kernels
 	local _dump_mode _new_dump_mode
 	local _has_changed _needs_reboot
 	local _old_ck _new_ck
@@ -1555,13 +1495,12 @@ reset_crashkernel()
 					derror "Option --fadump only valid on PPC"
 					exit 1
 				fi
-				_val=${_opt#*=}
-				if _dump_mode=$(get_dump_mode_by_fadump_val $_val); then
-					_fadump_val=$_val
-				else
+				_new_fadump=${_opt#*=}
+				if ! _dump_mode=$(get_dump_mode_by_fadump_val $_new_fadump); then
 					derror "failed to determine dump mode"
 					exit
 				fi
+				[[ "$_new_fadump" == off ]] && _new_fadump=""
 				;;
 			--kernel=*)
 				_val=${_opt#*=}
@@ -1598,29 +1537,6 @@ reset_crashkernel()
 
 	[[ $(uname -m) != ppc64le ]] && _dump_mode=kdump
 
-	# If the dump mode is determined, we can also know the default crashkernel value
-	if [[ -n $_dump_mode ]]; then
-		_crashkernel=$(kdump_get_arch_recommend_crashkernel "$_dump_mode")
-	fi
-
-	# If --kernel-path=ALL, update GRUB_CMDLINE_LINUX in /etc/default/grub.
-	#
-	# An exception case is when the ppc64le user doesn't specify the fadump value.
-	# In this case, the dump mode would be determined by parsing the kernel
-	# command line of the kernel(s) to be updated thus don't update GRUB_CMDLINE_LINUX.
-	#
-	# The following code has been simplified because of what has been done early,
-	#   - set the dump mode as kdump for non-ppc64le cases
-	#   - retrieved the default crashkernel value for given dump mode
-	if [[ $_grubby_kernel_path == ALL && -n $_dump_mode ]]; then
-		_update_kernel_arg_in_grub_etc_default crashkernel "$_crashkernel"
-		# remove the fadump if fadump is disabled
-		if [[ $_fadump_val == off ]]; then
-			_fadump_val=""
-		fi
-		_update_kernel_arg_in_grub_etc_default fadump "$_fadump_val"
-	fi
-
 	# If kernel-path not specified, either
 	#  - use KDUMP_KERNELVER if it's defined
 	#  - use current running kernel
@@ -1638,15 +1554,13 @@ reset_crashkernel()
 		_has_changed=""
 		if [[ -z $_dump_mode ]]; then
 			_new_dump_mode=$(get_dump_mode_by_kernel "$_kernel")
-			_new_ck=$(kdump_get_arch_recommend_crashkernel "$_new_dump_mode")
 			_new_fadump=$(get_grub_kernel_boot_parameter "$_kernel" fadump)
 		else
 			_new_dump_mode=$_dump_mode
-			_new_ck=$_crashkernel
-			_new_fadump=$_fadump_val
 		fi
 
 		_old_ck=$(get_grub_kernel_boot_parameter "$_kernel" crashkernel)
+		_new_ck=$(kdump_get_arch_recommend_crashkernel "$_new_dump_mode")
 		_old_fadump=$(get_grub_kernel_boot_parameter "$_kernel" fadump)
 		if _update_kernel_cmdline "$_kernel" fadump "$_old_fadump" "$_new_fadump"; then
 			_has_changed="Updated fadump=$_new_fadump"
diff --git a/spec/kdumpctl_general_spec.sh b/spec/kdumpctl_general_spec.sh
index 7304cd4..dcac2f8 100644
--- a/spec/kdumpctl_general_spec.sh
+++ b/spec/kdumpctl_general_spec.sh
@@ -155,73 +155,6 @@ Describe 'kdumpctl'
 		End
 	End
 
-	Describe '_update_kernel_arg_in_grub_etc_default()'
-		GRUB_ETC_DEFAULT=/tmp/default_grub
-
-		cleanup() {
-			rm -rf "$GRUB_ETC_DEFAULT"
-		}
-		AfterAll 'cleanup'
-
-		Context 'when the given parameter is in different positions'
-			Parameters
-				"crashkernel=222M fadump=on rhgb quiet" crashkernel 333M
-				" fadump=on crashkernel=222M rhgb quiet" crashkernel 333M
-				"fadump=on rhgb quiet crashkernel=222M" crashkernel 333M
-				"fadump=on rhgb quiet" crashkernel 333M
-				"fadump=on foo=bar1 rhgb quiet" foo bar2
-			End
-
-			It 'should update the kernel parameter correctly'
-				echo 'GRUB_CMDLINE_LINUX="'"$1"'"' >$GRUB_ETC_DEFAULT
-				When call _update_kernel_arg_in_grub_etc_default "$2" "$3"
-				# the updated kernel parameter should appear in the end
-				The contents of file $GRUB_ETC_DEFAULT should include "$2=$3\""
-			End
-		End
-
-		It 'should only update the given parameter and not update the parameter that has the given parameter as suffix'
-			echo 'GRUB_CMDLINE_LINUX="fadump=on rhgb quiet ckcrashkernel=222M"' >$GRUB_ETC_DEFAULT
-			_ck_val=1G-4G:192M,4G-64G:256M,64G-102400T:512M
-			When call _update_kernel_arg_in_grub_etc_default crashkernel "$_ck_val"
-			The contents of file $GRUB_ETC_DEFAULT should include "crashkernel=$_ck_val\""
-			The contents of file $GRUB_ETC_DEFAULT should include "ckcrashkernel=222M"
-		End
-
-		It 'should be able to handle the cases of there are multiple crashkernel entries'
-			echo 'GRUB_CMDLINE_LINUX="fadump=on rhgb quiet crashkernel=101M crashkernel=222M"' >$GRUB_ETC_DEFAULT
-			_ck_val=1G-4G:192M,4G-64G:256M,64G-102400T:512M
-			When call _update_kernel_arg_in_grub_etc_default crashkernel "$_ck_val"
-			The contents of file $GRUB_ETC_DEFAULT should include "crashkernel=$_ck_val\""
-			The contents of file $GRUB_ETC_DEFAULT should not include "crashkernel=222M"
-		End
-
-		Context 'when it removes a kernel parameter'
-
-			It 'should remove all values for given arg'
-				echo 'GRUB_CMDLINE_LINUX="crashkernel=33M crashkernel=11M fadump=on crashkernel=222M"' >$GRUB_ETC_DEFAULT
-				When call _update_kernel_arg_in_grub_etc_default crashkernel
-				The contents of file $GRUB_ETC_DEFAULT should equal 'GRUB_CMDLINE_LINUX="fadump=on"'
-			End
-
-			It 'should not remove args that have the given arg as suffix'
-				echo 'GRUB_CMDLINE_LINUX="ckcrashkernel=33M crashkernel=11M ckcrashkernel=222M"' >$GRUB_ETC_DEFAULT
-				When call _update_kernel_arg_in_grub_etc_default crashkernel
-				The contents of file $GRUB_ETC_DEFAULT should equal 'GRUB_CMDLINE_LINUX="ckcrashkernel=33M ckcrashkernel=222M"'
-			End
-		End
-
-	End
-
-	Describe '_read_kernel_arg_in_grub_etc_default()'
-		GRUB_ETC_DEFAULT=/tmp/default_grub
-		It 'should read the value for given arg'
-			echo 'GRUB_CMDLINE_LINUX="crashkernel=33M crashkernel=11M ckcrashkernel=222M"' >$GRUB_ETC_DEFAULT
-			When call _read_kernel_arg_in_grub_etc_default crashkernel
-			 The output should equal '11M'
-		End
-	End
-
 	Describe '_find_kernel_path_by_release()'
 		grubby() {
 			echo -e 'kernel="/boot/vmlinuz-6.2.11-200.fc37.x86_64"\nkernel="/boot/vmlinuz-5.14.0-322.el9.aarch64"\nkernel="/boot/vmlinuz-5.14.0-316.el9.aarch64+64k"'
diff --git a/spec/kdumpctl_reset_crashkernel_spec.sh b/spec/kdumpctl_reset_crashkernel_spec.sh
index 8fb4385..2e3b2ba 100644
--- a/spec/kdumpctl_reset_crashkernel_spec.sh
+++ b/spec/kdumpctl_reset_crashkernel_spec.sh
@@ -111,11 +111,6 @@ Describe 'kdumpctl reset-crashkernel [--kernel] [--fadump]'
 			fi
 		}
 
-		_update_kernel_arg_in_grub_etc_default() {
-			# don't modify /etc/default/grub during the test
-			echo _update_kernel_arg_in_grub_etc_default "$@"
-		}
-
 		kdump_crashkernel=$(get_default_crashkernel kdump)
 		fadump_crashkernel=$(get_default_crashkernel fadump)
 		Context "when no --kernel specified"
@@ -141,7 +136,6 @@ Describe 'kdumpctl reset-crashkernel [--kernel] [--fadump]'
 			grubby --args crashkernel=$ck --update-kernel ALL
 			Specify 'kdumpctl should warn the user that crashkernel has been udpated'
 				When call reset_crashkernel --kernel=ALL --fadump=on
-				The line 1 of output should include "_update_kernel_arg_in_grub_etc_default crashkernel $fadump_crashkernel"
 				The error should include "Updated crashkernel=$fadump_crashkernel for kernel=$kernel1"
 				The error should include "Updated crashkernel=$fadump_crashkernel for kernel=$kernel2"
 			End
@@ -200,8 +194,6 @@ Describe 'kdumpctl reset-crashkernel [--kernel] [--fadump]'
 			grubby --args fadump=on --update-kernel ALL
 			Specify 'fadump=on to fadump=nocma'
 				When call reset_crashkernel --kernel=ALL --fadump=nocma
-				The line 1 of output should equal "_update_kernel_arg_in_grub_etc_default crashkernel $fadump_crashkernel"
-				The line 2 of output should equal "_update_kernel_arg_in_grub_etc_default fadump nocma"
 				The error should include "Updated crashkernel=$fadump_crashkernel for kernel=$kernel1"
 				The error should include "Updated crashkernel=$fadump_crashkernel for kernel=$kernel2"
 			End
@@ -213,8 +205,6 @@ Describe 'kdumpctl reset-crashkernel [--kernel] [--fadump]'
 
 			Specify 'fadump=nocma to fadump=on'
 				When call reset_crashkernel --kernel=ALL --fadump=on
-				The line 1 of output should equal "_update_kernel_arg_in_grub_etc_default crashkernel $fadump_crashkernel"
-				The line 2 of output should equal "_update_kernel_arg_in_grub_etc_default fadump on"
 				The error should include "Updated fadump=on for kernel=$kernel1"
 			End