From 460dbb513d953e7864c88ae831e6431792c306e0 Mon Sep 17 00:00:00 2001
From: Helmut Grohne <helmut@subdivi.de>
Date: Wed, 7 Jun 2023 09:31:54 +0200
Subject: debvm-run: add an --append option

Unlike qemu's -append, it has append semantics both to repeated use and
to internal defaults.
---
 bin/debvm-run | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

(limited to 'bin/debvm-run')

diff --git a/bin/debvm-run b/bin/debvm-run
index f1cde97..53e2ba3 100755
--- a/bin/debvm-run
+++ b/bin/debvm-run
@@ -24,6 +24,12 @@ A net interface configured for user mode is added automatically.
 
 =over 8
 
+=item B<--append>=I<cmdline>
+
+While the kernel command line can be modified by passing B<-append> to B<qemu> directly, doing that always replaces the entire command line and thus removes important values passed by B<debvm-run>.
+This variant instead appends given command line arguments to the automatic ones.
+Repeated use also causes appending rather than replacement.
+
 =item B<-g>, B<--graphical>
 
 By default, the option B<-nographic> is passed to B<qemu> and one interacts with the serial console of the machine.
@@ -96,6 +102,7 @@ set -u
 IMAGE=rootfs.ext4
 SSHPORT=
 GRAPHICAL=
+CMDLINE_APPEND=
 
 nth_arg() {
 	shift "$1"
@@ -122,6 +129,9 @@ usage_error() {
 	usage
 }
 
+opt_append() {
+	CMDLINE_APPEND="${CMDLINE_APPEND:+$CMDLINE_APPEND }$1"
+}
 opt_graphical() {
 	GRAPHICAL=1
 }
@@ -145,12 +155,12 @@ while getopts :gi:s:-: OPTCHAR; do
 				graphical)
 					"opt_$OPTARG"
 				;;
-				image|sshport)
+				append|image|sshport)
 					test "$OPTIND" -gt "$#" && usage_error "missing argument for --$OPTARG"
 					"opt_$OPTARG" "$(nth_arg "$OPTIND" "$@")"
 					OPTIND=$((OPTIND+1))
 				;;
-				image=*|sshport=*)
+				append=|image=*|sshport=*)
 					"opt_${OPTARG%%=*}" "${OPTARG#*=}"
 				;;
 				*)
@@ -385,7 +395,7 @@ if test -n "$DNSSEARCH"; then
 	NETDEV="$NETDEV,domainname=$DNSSEARCH"
 fi
 set -- \
-	-append "$KERNEL_CMDLINE" \
+	-append "$KERNEL_CMDLINE${CMDLINE_APPEND:+ $CMDLINE_APPEND}" \
 	-netdev "$NETDEV" \
 	-device "$NIC_DEV" \
 	"$@"
-- 
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