[Qemu-devel] [PATCH v3 2/2] cdrom: Make disc change event visible to guests

[Amit Shah]

Commit 93c8cfd9e67a62711b86f4c93747566885eb7928 sent a 'no disc' event
after a cdrom change so that guests notice a cd change event between two
'cd present' states.  However, we don't follow the 2nd arrow in:

 'cd present' -> 'no cd' -> 'cd present'

as the SENSE_UNIT_ATTENTION sense_key is written over by the
ide_atapi_cmd_error() function.

So for the disc change event, let us ensure the error() function doesn't
trample over that value so we do get to report it the next time around.
Also, ensure we go from 'no cd' to 'cd present' state.

With this, older Linux guests (< 2.6.38) notice cd changes just fine.
For newer Linux guests (2.6.38+) cd change events break again and that
will be fixed by implementing the GET_EVENT_STATUS_NOTIFICATION command.

Signed-off-by: Amit Shah <address@hidden>
---
 hw/ide/core.c |   47 ++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index d55d804..3f00cff 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1113,10 +1113,47 @@ static void ide_atapi_cmd(IDEState *s)
     }
     switch(s->io_buffer[0]) {
     case GPCMD_TEST_UNIT_READY:
-        if (bdrv_is_inserted(s->bs) && !s->cdrom_changed) {
-            ide_atapi_cmd_ok(s);
+        if (bdrv_is_inserted(s->bs)) {
+            int sense, asc;
+
+            sense = s->sense_key;
+            asc = s->asc;
+
+            /*
+             * Check if there's any pending media change notification
+             * to be given.
+             *
+             * We want the guest to notice an empty tray after a cd
+             * change, so that the guest can trigger its new media
+             * paths.  So send one MEDIUM_NOT_PRESENT message after a
+             * cd change.
+             *
+             * After we've sent that message, the guest will poke at
+             * us again.  Send the UNIT_ATTENTION message then.  Once
+             * this is done, reset the UNIT_ATTENTION message to
+             * ensure we don't keep repeating it.
+             */
+            switch(s->cdrom_changed) {
+            case 0:
+                ide_atapi_cmd_ok(s);
+                break;
+            case 1:
+                s->sense_key = SENSE_UNIT_ATTENTION;
+                s->asc = ASC_MEDIUM_MAY_HAVE_CHANGED;
+                ide_atapi_cmd_ok(s);
+
+               sense = SENSE_NONE;
+                s->cdrom_changed--;
+                break;
+            case 2:
+                ide_atapi_cmd_error(s, SENSE_NOT_READY,
+                                    ASC_MEDIUM_NOT_PRESENT);
+                s->cdrom_changed--;
+                break;
+            }
+            s->sense_key = sense;
+            s->asc = asc;
         } else {
-            s->cdrom_changed = 0;
             ide_atapi_cmd_error(s, SENSE_NOT_READY,
                                 ASC_MEDIUM_NOT_PRESENT);
         }
@@ -1612,7 +1649,7 @@ static void cdrom_change_cb(void *opaque, int reason)
 
     s->sense_key = SENSE_UNIT_ATTENTION;
     s->asc = ASC_MEDIUM_MAY_HAVE_CHANGED;
-    s->cdrom_changed = 1;
+    s->cdrom_changed = 2;
     ide_set_irq(s->bus);
 }
 
@@ -2712,7 +2749,7 @@ static int ide_drive_post_load(void *opaque, int 
version_id)
     if (version_id < 3) {
         if (s->sense_key == SENSE_UNIT_ATTENTION &&
             s->asc == ASC_MEDIUM_MAY_HAVE_CHANGED) {
-            s->cdrom_changed = 1;
+            s->cdrom_changed = 2;
         }
     }
     return 0;
-- 
1.7.4