[Qemu-devel] [PATCH] Fix media detection on emulated CDROM

[Qemu-devel] [PATCH] Fix media detection on emulated CDROM

[Gary Grebus]

This patch tweaks the ATAPI CDROM emulation to fix an annoyance seen
when running a variety of Linux guests: the desktop GUI shows a CDROM
device as present, but is unable to automount the media and display its
contents.

The patch adds the PLAY_AUDIO capability bit to the data returned by
MODE_SENSE commands.  That convinces the guest kernel to determine what
kind of media is present.

Arguably Linux could be smarter about this, but it's my guess there are
few (if any) hardware CDROM drives that don't set the bit, and there are
a large number of Linux distros that exhibit this problem.

Signed-off-by: Gary Grebus <ggrebus@virtualiron.com>

-- 
Gary Grebus
Virtual Iron Software, Inc.

Index: hw/ide.c
===================================================================
--- hw/ide.c	(revision 5729)
+++ hw/ide.c	(working copy)
@@ -1603,7 +1603,7 @@
                     buf[10] = 0x00;
                     buf[11] = 0x00;
 
-                    buf[12] = 0x70;
+                    buf[12] = 0x71;
                     buf[13] = 3 << 5;
                     buf[14] = (1 << 0) | (1 << 3) | (1 << 5);
                     if (bdrv_is_locked(s->bs))

Re: [Qemu-devel] [PATCH] Fix media detection on emulated CDROM

[Anthony Liguori]

Gary Grebus wrote:
> This patch tweaks the ATAPI CDROM emulation to fix an annoyance seen
> when running a variety of Linux guests: the desktop GUI shows a CDROM
> device as present, but is unable to automount the media and display its
> contents.
>
> The patch adds the PLAY_AUDIO capability bit to the data returned by
> MODE_SENSE commands.  That convinces the guest kernel to determine what
> kind of media is present.
>
> Arguably Linux could be smarter about this, but it's my guess there are
> few (if any) hardware CDROM drives that don't set the bit, and there are
> a large number of Linux distros that exhibit this problem.
>
> Signed-off-by: Gary Grebus <ggrebus@virtualiron.com>
>
>   

Could you please include a comment to this effect in the code?

Regards,

Anthony Liguori

Re: [Qemu-devel] [PATCH] Fix media detection on emulated CDROM

[Gary Grebus]

On Tue, 2008-11-18 at 13:18 -0600, Anthony Liguori wrote:
> Gary Grebus wrote:
> > This patch tweaks the ATAPI CDROM emulation to fix an annoyance seen
> > when running a variety of Linux guests: the desktop GUI shows a CDROM
> > device as present, but is unable to automount the media and display its
> > contents.
> >
> > The patch adds the PLAY_AUDIO capability bit to the data returned by
> > MODE_SENSE commands.  That convinces the guest kernel to determine what
> > kind of media is present.
> >
> > Arguably Linux could be smarter about this, but it's my guess there are
> > few (if any) hardware CDROM drives that don't set the bit, and there are
> > a large number of Linux distros that exhibit this problem.
> >
> > Signed-off-by: Gary Grebus <ggrebus@virtualiron.com>
> >
> >   
> 
> Could you please include a comment to this effect in the code?
> 
> Regards,
> 
> Anthony Liguori

No problem... revised patch below.

-- 
Gary Grebus
Virtual Iron Software, Inc.


Index: hw/ide.c
===================================================================
--- hw/ide.c	(revision 5729)
+++ hw/ide.c	(working copy)
@@ -1603,7 +1603,9 @@
                     buf[10] = 0x00;
                     buf[11] = 0x00;
 
-                    buf[12] = 0x70;
+                    /* Claim PLAY_AUDIO capability (0x01) since some Linux
+                       code checks for this to automount media. */
+                    buf[12] = 0x71;
                     buf[13] = 3 << 5;
                     buf[14] = (1 << 0) | (1 << 3) | (1 << 5);
                     if (bdrv_is_locked(s->bs))

Re: [Qemu-devel] [PATCH] Fix media detection on emulated CDROM

[Anthony Liguori]

Gary Grebus wrote:
> On Tue, 2008-11-18 at 13:18 -0600, Anthony Liguori wrote:
>   
> No problem... revised patch below.
>   

Applied. Thanks.

Regards,

Anthony Liguori