diff --git a/kdump-lib.sh b/kdump-lib.sh
index 1c68e6a..88fea64 100755
--- a/kdump-lib.sh
+++ b/kdump-lib.sh
@@ -977,3 +977,74 @@ get_all_kdump_crypt_dev()
[[ -n "$_crypt" ]] && echo $_crypt
done
}
+
+check_vmlinux()
+{
+ # Use readelf to check if it's a valid ELF
+ readelf -h $1 &>/dev/null || return 1
+}
+
+get_vmlinux_size()
+{
+ local size=0
+
+ while read _type _offset _virtaddr _physaddr _fsize _msize _flg _aln; do
+ size=$(( $size + $_msize ))
+ done <<< $(readelf -l -W $1 | grep "^ LOAD" 2>/dev/stderr)
+
+ echo $size
+}
+
+try_decompress()
+{
+ # The obscure use of the "tr" filter is to work around older versions of
+ # "grep" that report the byte offset of the line instead of the pattern.
+
+ # Try to find the header ($1) and decompress from here
+ for pos in `tr "$1\n$2" "\n$2=" < "$4" | grep -abo "^$2"`
+ do
+ if ! type -P $3 > /dev/null; then
+ ddebug "Signiature detected but '$3' is missing, skip this decompressor"
+ break
+ fi
+
+ pos=${pos%%:*}
+ tail -c+$pos "$img" | $3 > $5 2> /dev/null
+ if check_vmlinux $5; then
+ ddebug "Kernel is extracted with '$3'"
+ return 0
+ fi
+ done
+
+ return 1
+}
+
+# Borrowed from linux/scripts/extract-vmlinux
+get_kernel_size()
+{
+ # Prepare temp files:
+ local img=$1 tmp=$(mktemp /tmp/vmlinux-XXX)
+ trap "rm -f $tmp" 0
+
+ # Try to check if it's a vmlinux already
+ check_vmlinux $img && get_vmlinux_size $img && return 0
+
+ # That didn't work, so retry after decompression.
+ try_decompress '\037\213\010' xy gunzip $img $tmp || \
+ try_decompress '\3757zXZ\000' abcde unxz $img $tmp || \
+ try_decompress 'BZh' xy bunzip2 $img $tmp || \
+ try_decompress '\135\0\0\0' xxx unlzma $img $tmp || \
+ try_decompress '\211\114\132' xy 'lzop -d' $img $tmp || \
+ try_decompress '\002!L\030' xxx 'lz4 -d' $img $tmp || \
+ try_decompress '(\265/\375' xxx unzstd $img $tmp
+
+ # Finally check for uncompressed images or objects:
+ [[ $? -eq 0 ]] && get_vmlinux_size $tmp && return 0
+
+ # Fallback to use iomem
+ local _size=0
+ for _seg in $(cat /proc/iomem | grep -E "Kernel (code|rodata|data|bss)" | cut -d ":" -f 1); do
+ _size=$(( $_size + 0x${_seg#*-} - 0x${_seg%-*} ))
+ done
+ echo $_size
+}
diff --git a/kdumpctl b/kdumpctl
index 24f5cf7..37d8c51 100755
--- a/kdumpctl
+++ b/kdumpctl
@@ -1214,6 +1214,97 @@ rebuild() {
return $?
}
+do_estimate() {
+ local kdump_mods
+ local -A large_mods
+ local baseline
+ local kernel_size mod_size initrd_size baseline_size runtime_size reserved_size estimated_size recommanded_size
+ local size_mb=$(( 1024 * 1024 ))
+
+ setup_initrd
+ if [ ! -f "$TARGET_INITRD" ]; then
+ derror "kdumpctl estimate: kdump initramfs is not built yet."
+ exit 1
+ fi
+
+ kdump_mods="$(lsinitrd "$TARGET_INITRD" -f /usr/lib/dracut/hostonly-kernel-modules.txt | tr '\n' ' ')"
+ baseline=$(kdump_get_arch_recommend_size)
+ if [[ "${baseline: -1}" == "M" ]]; then
+ baseline=${baseline%M}
+ elif [[ "${baseline: -1}" == "G" ]]; then
+ baseline=$(( ${baseline%G} * 1024 ))
+ elif [[ "${baseline: -1}" == "T" ]]; then
+ baseline=$(( ${baseline%Y} * 1048576 ))
+ fi
+
+ # The default value when using crashkernel=auto
+ baseline_size=$((baseline * size_mb))
+ # Current reserved crashkernel size
+ reserved_size=$(cat /sys/kernel/kexec_crash_size)
+ # A pre-estimated value for userspace usage and kernel
+ # runtime allocation, 64M should good for most cases
+ runtime_size=$((64 * size_mb))
+ # Kernel image size
+ kernel_size=$(get_kernel_size "$KDUMP_KERNEL")
+ # Kdump initramfs size
+ initrd_size=$(du -b "$TARGET_INITRD" | awk '{print $1}')
+ # Kernel modules static size after loaded
+ mod_size=0
+ while read -r _name _size _; do
+ if [[ ! " $kdump_mods " == *" $_name "* ]]; then
+ continue
+ fi
+ mod_size=$((mod_size + _size))
+
+ # Mark module with static size larger than 2M as large module
+ if [[ $((_size / size_mb)) -ge 1 ]]; then
+ large_mods[$_name]=$_size
+ fi
+ done <<< "$(< /proc/modules)"
+
+ # Extra memory usage required for LUKS2 decryption
+ crypt_size=0
+ for _dev in $(get_all_kdump_crypt_dev); do
+ _crypt_info=$(cryptsetup luksDump "/dev/block/$_dev")
+ [[ $(echo "$_crypt_info" | sed -n "s/^Version:\s*\(.*\)/\1/p" ) == "2" ]] || continue
+ for _mem in $(echo "$_crypt_info" | sed -n "s/\sMemory:\s*\(.*\)/\1/p" | sort -n ); do
+ crypt_size=$((crypt_size + _mem * 1024))
+ break
+ done
+ done
+ [[ $crypt_size -ne 0 ]] && echo -e "Encrypted kdump target requires extra memory, assuming using the keyslot with minimun memory requirement\n"
+
+ estimated_size=$((kernel_size + mod_size + initrd_size + runtime_size + crypt_size))
+ if [[ $baseline_size -gt $estimated_size ]]; then
+ recommanded_size=$baseline_size
+ else
+ recommanded_size=$estimated_size
+ fi
+
+ echo "Reserved crashkernel: $((reserved_size / size_mb))M"
+ echo "Recommanded crashkernel: $((recommanded_size / size_mb))M"
+ echo
+ echo "Kernel image size: $((kernel_size / size_mb))M"
+ echo "Kernel modules size: $((mod_size / size_mb))M"
+ echo "Initramfs size: $((initrd_size / size_mb))M"
+ echo "Runtime reservation: $((runtime_size / size_mb))M"
+ [[ $crypt_size -ne 0 ]] && \
+ echo "LUKS required size: $((crypt_size / size_mb))M"
+ echo -n "Large modules:"
+ if [[ "${#large_mods[@]}" -eq 0 ]]; then
+ echo " <none>"
+ else
+ echo ""
+ for _mod in "${!large_mods[@]}"; do
+ echo " $_mod: ${large_mods[$_mod]}"
+ done
+ fi
+
+ if [[ $reserved_size -lt $recommanded_size ]]; then
+ echo "WARNING: Current crashkernel size is lower than recommanded size $((recommanded_size / size_mb))M."
+ fi
+}
+
if [ ! -f "$KDUMP_CONFIG_FILE" ]; then
derror "Error: No kdump config file found!"
exit 1
@@ -1269,8 +1360,11 @@ main ()
showmem)
show_reserved_mem
;;
+ estimate)
+ do_estimate
+ ;;
*)
- dinfo $"Usage: $0 {start|stop|status|restart|reload|rebuild|propagate|showmem}"
+ dinfo $"Usage: $0 {estimate|start|stop|status|restart|reload|rebuild|propagate|showmem}"
exit 1
esac
}
diff --git a/kdumpctl.8 b/kdumpctl.8
index ae97af7..a32a972 100644
--- a/kdumpctl.8
+++ b/kdumpctl.8
@@ -44,6 +44,11 @@ impossible to use password authentication during kdump.
.TP
.I showmem
Prints the size of reserved memory for crash kernel in megabytes.
+.TP
+.I estimate
+Estimate a suitable crashkernel value for current machine. This is a
+best-effort estimate. It will print a recommanded crashkernel value
+based on current kdump setup, and list some details of memory usage.
.SH "SEE ALSO"
.BR kdump.conf (5),