boot: introduce parameter for optional kernel command line

in functions used to update it.

boot/boot.go

@@ -24,6 +24,7 @@ import (
 	"fmt"
 
 	"github.com/snapcore/snapd/bootloader"
+	"github.com/snapcore/snapd/logger"
 	"github.com/snapcore/snapd/snap"
 )
 
@@ -429,21 +430,23 @@ func SetRecoveryBootSystemAndMode(dev snap.Device, systemLabel, mode string) err
 	return bl.SetBootVars(m)
 }
 
-// UpdateManagedBootConfigs updates managed boot config assets if those are
-// present for the ubuntu-boot bootloader. Returns true when an update was
-// carried out.
-func UpdateManagedBootConfigs(dev snap.Device, gadgetSnapOrDir string) (updated bool, err error) {
+// UpdateManagedBootConfigs updates managed boot config assets if
+// those are present for the ubuntu-boot bootloader. To do this it
+// needs information from the model, the gadget we are updating to,
+// and any additional kernel command line arguments coming from system
+// options. Returns true when an update was carried out.
+func UpdateManagedBootConfigs(dev snap.Device, gadgetSnapOrDir, cmdlineAppend string) (updated bool, err error) {
 	if !dev.HasModeenv() {
 		// only UC20 devices use managed boot config
 		return false, nil
 	}
 	if !dev.RunMode() {
 		return false, fmt.Errorf("internal error: boot config can only be updated in run mode")
 	}
-	return updateManagedBootConfigForBootloader(dev, ModeRun, gadgetSnapOrDir)
+	return updateManagedBootConfigForBootloader(dev, ModeRun, gadgetSnapOrDir, cmdlineAppend)
 }
 
-func updateManagedBootConfigForBootloader(dev snap.Device, mode, gadgetSnapOrDir string) (updated bool, err error) {
+func updateManagedBootConfigForBootloader(dev snap.Device, mode, gadgetSnapOrDir, cmdlineAppend string) (updated bool, err error) {
 	if mode != ModeRun {
 		return false, fmt.Errorf("internal error: updating boot config of recovery bootloader is not supported yet")
 	}
@@ -461,18 +464,20 @@ func updateManagedBootConfigForBootloader(dev snap.Device, mode, gadgetSnapOrDir
 		return false, err
 	}
 	// boot config update can lead to a change of kernel command line
-	_, err = observeCommandLineUpdate(dev.Model(), commandLineUpdateReasonSnapd, gadgetSnapOrDir)
+	_, err = observeCommandLineUpdate(dev.Model(), commandLineUpdateReasonSnapd, gadgetSnapOrDir, cmdlineAppend)
 	if err != nil {
 		return false, err
 	}
 	return tbl.UpdateBootConfig()
 }
 
-// UpdateCommandLineForGadgetComponent handles the update of a gadget that
-// contributes to the kernel command line of the run system. Returns true when a
-// change in command line has been observed and a reboot is needed. The reboot,
-// if needed, should be requested at the the earliest possible occasion.
-func UpdateCommandLineForGadgetComponent(dev snap.Device, gadgetSnapOrDir string) (needsReboot bool, err error) {
+// UpdateCommandLineForGadgetComponent handles the update of a gadget
+// that contributes to the kernel command line of the run system
+// (appending any additional kernel command line arguments coming from
+// system options). Returns true when a change in command line has
+// been observed and a reboot is needed. The reboot, if needed, should
+// be requested at the the earliest possible occasion.
+func UpdateCommandLineForGadgetComponent(dev snap.Device, gadgetSnapOrDir, cmdlineAppend string) (needsReboot bool, err error) {
 	if !dev.HasModeenv() {
 		// only UC20 devices are supported
 		return false, fmt.Errorf("internal error: command line component cannot be updated on pre-UC20 devices")
@@ -490,8 +495,9 @@ func UpdateCommandLineForGadgetComponent(dev snap.Device, gadgetSnapOrDir string
 		}
 		return false, err
 	}
+
 	// gadget update can lead to a change of kernel command line
-	cmdlineChange, err := observeCommandLineUpdate(dev.Model(), commandLineUpdateReasonGadget, gadgetSnapOrDir)
+	cmdlineChange, err := observeCommandLineUpdate(dev.Model(), commandLineUpdateReasonGadget, gadgetSnapOrDir, cmdlineAppend)
 	if err != nil {
 		return false, err
 	}
@@ -500,10 +506,11 @@ func UpdateCommandLineForGadgetComponent(dev snap.Device, gadgetSnapOrDir string
 	}
 	// update the bootloader environment, maybe clearing the relevant
 	// variables
-	cmdlineVars, err := bootVarsForTrustedCommandLineFromGadget(gadgetSnapOrDir)
+	cmdlineVars, err := bootVarsForTrustedCommandLineFromGadget(gadgetSnapOrDir, cmdlineAppend)
 	if err != nil {
 		return false, fmt.Errorf("cannot prepare bootloader variables for kernel command line: %v", err)
 	}
+	logger.Debugf("updating boot vars: %v", cmdlineVars)
 	if err := tbl.SetBootVars(cmdlineVars); err != nil {
 		return false, fmt.Errorf("cannot set run system kernel command line arguments: %v", err)
 	}