fix(test): select persistent UEFI test media without changing boot order

dev/iso-smoke.py

@@ -635,7 +635,7 @@ def qemu_path(path):
     return str(path)
 
 
-def qemu_argv(qemu, scratch, disk, code, variables, iso, memory):
+def qemu_argv(qemu, scratch, disk, code, variables, iso, memory, *, keep_cdrom_drive=False):
     scratch = Path(scratch)
     owned_file(disk, scratch)
     owned_file(variables, scratch)
@@ -650,8 +650,17 @@ def qemu_argv(qemu, scratch, disk, code, variables, iso, memory):
     if iso is not None:
         if not Path(iso).is_file():
             raise SmokeError('Trusted ISO must exist as a regular file')
-        argv += ['-drive', f'file={qemu_path(iso)},media=cdrom,format=raw,readonly=on',
-                 '-boot', 'order=d,strict=on']
+    if keep_cdrom_drive:
+        # Keep one SATA0 device even without media so OVMF retains its DVD boot
+        # entry across ISO-free boots. No file= means there is no optical medium.
+        optical = 'if=ide,index=0,id=acceptance-cdrom,media=cdrom,readonly=on'
+        if iso is not None:
+            optical += ',format=raw,file=' + qemu_path(iso)
+        argv += ['-drive', optical]
+    elif iso is not None:
+        argv += ['-drive', f'file={qemu_path(iso)},media=cdrom,format=raw,readonly=on']
+    if iso is not None:
+        argv += ['-boot', 'order=d,strict=on']
     else:
         argv += ['-boot', 'order=c,strict=on']
     return argv
@@ -816,7 +825,8 @@ class VM:
             (scratch / name).unlink(missing_ok=True)
         self.stderr = open(scratch / f'{phase}-qemu.log', 'ab', buffering=0)
         self.process = subprocess.Popen(qemu_argv(args.qemu, scratch, disk,
-            args.ovmf_code, scratch / 'OVMF_VARS.fd', iso, args.memory),
+            args.ovmf_code, scratch / 'OVMF_VARS.fd', iso, args.memory,
+            keep_cdrom_drive=getattr(args, 'keep_cdrom_drive', False)),
             stdin=subprocess.DEVNULL, stdout=self.stderr, stderr=self.stderr)
         self.console = None
         self.qmp = None