scripts: Support a root disk connected via virtio-scsi

Sometimes it is useful to use SCSI instead of the plain virtio. Add a
-S option to connect the root disk via SCSI.

Drop the -S for --sct-seq since it is a less common option.

Signed-off-by: Simon Glass <sjg@chromium.org>

scripts/build-qemu

@@ -52,7 +52,7 @@ def parse_args():
     parser.add_argument('-x', '--xpl', action='store_true',
                         help='Use xPL image rather than U-Boot proper')
     parser.add_argument(
-        '-S', '--sct-seq',
+        '--sct-seq',
         help='SCT sequence-file to be written into the SCT image if -e')
     parser.add_argument('-v', '--verbose', action='store_true',
                         help='Show executed commands')

scripts/build_helper.py

@@ -26,6 +26,8 @@ from u_boot_pylib import tools
 from u_boot_pylib import tout
 import fs_helper
 
+MODERN_PCI = 'disable-legacy=on,disable-modern=off'
+
 
 class Helper:
     def __init__(self, args):
@@ -163,13 +165,18 @@ sct_mnt = /mnt/sct
 
         if self.img_fname:
             if self.img_fname.exists():
+                iface = 'none' if args.scsi else 'virtio'
+                if args.scsi:
+                    cmd.extend([
+                        '-device',
+                        f'virtio-scsi-pci,id=scsi0,{MODERN_PCI}',
+                        '-device', 'scsi-hd,bus=scsi0.0,drive=hd0'])
                 cmd.extend([
                     '-drive',
-                    f'if=virtio,file={self.img_fname},format=raw,id=hd1'])
+                    f'if={iface},file={self.img_fname},format=raw,id=hd0'])
             else:
                 tout.warning(f"Disk image '{self.img_fname}' not found")
 
-
 def add_common_args(parser):
     """Add some arguments which are common to build-efi/qemu scripts
 
@@ -200,6 +207,9 @@ def add_common_args(parser):
         help='Select OS release version (e.g, 24.04) Default: 24.04.1')
     parser.add_argument('-s', '--serial-only', action='store_true',
                         help='Run QEMU with serial only (no display)')
+    parser.add_argument(
+        '-S', '--scsi', action='store_true',
+        help='Attach root disk using virtio-sci instead of virtio-blk')
     parser.add_argument(
         '-t', '--root',
         help='Pass the given root device to linux via root=xxx')