Re: regression: xen domU no longer supports "type=cdrom" vbd disk

[Chavdar Ivanov <ci4ic4%gmail.com@localhost>]

On Mon, 8 Jun 2020 at 22:26, Greg A. Woods <woods%planix.ca@localhost> wrote:
>
> I use xl.cfg "disk" entries like the following to mount a virtual CDROM
> in a Xen domU:
>
>     'format=raw, vdev=0x5, access=ro, devtype=cdrom, target=/images/NetBSD-9.0-amd64.iso'
>
> However since upgrading my -current source tree I've been seeing:
>
>         xenbus0: ignoring device/vbd/4 type cdrom
>
> As shown in this patch I had to comment out the core of the mentioned
> change to be able to use an ISO image again as a virtual CDROM again:
>
>
> --- xenbus_probe.c.~1.55.~      2020-05-30 17:32:39.672816814 -0700
> +++ xenbus_probe.c      2020-06-08 14:13:45.025527521 -0700
> @@ -443,6 +443,14 @@
>                                 kmem_free(xbusd, xbusd->xbusd_sz);
>                                 break;
>                         }
> +//revision 1.51
> +//date: 2020-04-28 06:21:01 -0700;  author: bouyer;  state: Exp;  lines: +30 -9;  commitid: 5XOy6F9zbgN8C96C;
> +//Skip block device  with device-type "cdrom", as their emulation can't be
> +//disabled; and the backend driver doesn't handle them either.
> +//Fix hang when booting with 'ioemu:hdc:cdrom' type disks.
> +//While there convert some printf to aprint_error()
> +//
> +#if 0 /* XXX breaks use of ISO files! */
>                         if (strcmp(xa.xa_type, "vbd") == 0) {
>                                 char dtype[10];
>                                 if (xenbus_read(NULL, xbusd->xbusd_path,
> @@ -461,6 +469,7 @@
>                                         continue;
>                                 }
>                         }
> +#endif
>                         err = read_backend_details(xbusd);
>                         if (err != 0) {
>                                 aprint_error_dev(xenbus_dev,
>
>
> Now it works again:
>
>         xbd4 at xenbus0 id 4: Xen Virtual Block Device Interface
>         xbd4: using event channel 12
>         ...
>         boot device: xbd4
>         root on xbd4a dumps on xbd4b
>         root file system type: cd9660

I believe this was necessary at least under XCP-NG in PVHVM mode with
platform:viridian set to false - before the change the CD-ROM had to
be unconfigured as the system was hanging. After the change this was
no longer necessary and the CD-ROM was available.

>
> --
>                                         Greg A. Woods <gwoods%acm.org@localhost>
>
> Kelowna, BC     +1 250 762-7675           RoboHack <woods%robohack.ca@localhost>
> Planix, Inc. <woods%planix.com@localhost>     Avoncote Farms <woods%avoncote.ca@localhost>



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