virt-install: Add lots of warnings if --nographics won't work

man/virt-install.pod

@@ -265,25 +265,37 @@ virt-install will download kernel/initrd to the local machine, and then
 upload the media to the remote host. This option requires the URL to
 be accessible by both the local and remote host.
 
+--location allows things like --extra-args for kernel arguments, and using --initrd-inject. If you want to use those options with CDROM media, you have a few options:
+
+* Run virt-install as root and do --location ISO
+
+* Mount the ISO at a local directory, and do --location DIRECTORY
+
+* Mount the ISO at a local directory, export that directory over local http, and do --location http://localhost/DIRECTORY
+
 The C<LOCATION> can take one of the following forms:
 
 =over 4
 
-=item DIRECTORY
-
-Path to a local directory containing an installable distribution image
-
-=item nfs:host:/path or nfs://host/path
-
-An NFS server location containing an installable distribution image
-
 =item http://host/path
 
-An HTTP server location containing an installable distribution image
+An HTTP server location containing an installable distribution image.
 
 =item ftp://host/path
 
-An FTP server location containing an installable distribution image
+An FTP server location containing an installable distribution image.
+
+=item nfs:host:/path or nfs://host/path
+
+An NFS server location containing an installable distribution image. This requires running virt-install as root.
+
+=item DIRECTORY
+
+Path to a local directory containing an installable distribution image. Note that the directory will not be accessible by the guest after initial boot, so the OS installer will need another way to access the rest of the install media.
+
+=item ISO
+
+Mount the ISO and probe the directory. This requires running virt-install as root, and has the same VM access caveat as DIRECTORY.
 
 =back
 

virt-install

@@ -453,10 +453,77 @@ def check_option_collisions(options, guest):
         guest.conn.support_remote_url_install()):
         fail(_("Libvirt version does not support remote --location installs"))
 
+    cdrom_err = ""
+    if guest.installer.cdrom:
+        cdrom_err = " " + _("See the man page for examples of "
+            "using --location with CDROM media")
     if not options.location and options.extra_args:
-        fail(_("--extra-args only work if specified with --location."))
+        fail(_("--extra-args only work if specified with --location.") +
+             cdrom_err)
     if not options.location and options.initrd_inject:
-        fail(_("--initrd-inject only works if specified with --location."))
+        fail(_("--initrd-inject only works if specified with --location.") +
+             cdrom_err)
+
+
+def _show_nographics_warnings(options, guest):
+    if guest.get_devices("graphics"):
+        return
+    if not options.autoconsole:
+        return
+
+    if guest.installer.cdrom:
+        logging.warn(_("CDROM media does not print to the text console "
+            "by default, so you likely will not see text install output. "
+            "You might want to use --location."))
+        return
+
+    if not options.location:
+        return
+
+    # Trying --location --nographics with console connect. Warn if
+    # they likely won't see any output.
+
+    if not guest.get_devices("console"):
+        logging.warn(_("No --console device added, you likely will not "
+            "see text install output from the guest."))
+        return
+
+    serial_arg = "console=ttyS0"
+    virtio_arg = "console=hvc0"
+    console_type = None
+    if guest.conn.is_test() or guest.conn.is_qemu():
+        console_type = serial_arg
+        if guest.get_devices("console")[0].target_type == "virtio":
+            console_type = virtio_arg
+
+    if not options.extra_args or "console=" not in options.extra_args:
+        logging.warn(_("No 'console' seen in --extra-args, a '%s' kernel "
+            "argument is likely required to see text install output from "
+            "the guest."), console_type or "console=")
+        return
+
+    if console_type in options.extra_args:
+        return
+    if (serial_arg not in options.extra_args and
+        virtio_arg not in options.extra_args):
+        return
+
+    has = (serial_arg in options.extra_args) and serial_arg or virtio_arg
+    need = (serial_arg in options.extra_args) and virtio_arg or serial_arg
+    logging.warn(_("'%s' found in --extra-args, but the device attached "
+        "to the guest likely requires '%s'. You may not see text install "
+        "output from the guest."), has, need)
+    if has == serial_arg:
+        logging.warn(_("To make '--extra-args %s' work, you can force a "
+            "plain serial device with '--console pty'"), serial_arg)
+
+
+def show_warnings(options, guest):
+    if options.pxe and not supports_pxe(guest):
+        logging.warn(_("The guest's network configuration does not support "
+                       "PXE"))
+
+    _show_nographics_warnings(options, guest)
 
 
 ##########################
@@ -547,10 +614,7 @@ def build_guest_instance(conn, options, parsermap):
     # this after setting guest.installer at least
     check_option_collisions(options, guest)
 
-    # Warnings
-    if options.pxe and not supports_pxe(guest):
-        logging.warn(_("The guest's network configuration does not support "
-                       "PXE"))
+    show_warnings(options, guest)
 
     return guest