Re: [Qemu-devel] [PATCH] don't exit if cdrom media fails to open

[Mark McLoughlin <markmc@redhat.com>]

Hi David,

On Tue, 2009-06-09 at 07:41 -0600, David Ahern wrote:
> This patch allows a VM to continue even if the cdrom image is not
> accessible at VM boot time. It allows a boot progression similar to real
> hardware (e.g., try cd, then disk).
> 
> For example,
> 
> qemu-system-x86_64 -cdrom /dev/dvd -hda disk.img -boot dc
> 
> If there is no media in the tray, qemu currently exits with the message:
> qemu: could not open disk image /dev/dvd
> 
> With this patch, the message is still displayed, but qemu continues. It
> first tries to boot from the cdrom and then falls back to the disk.
> 
> Signed-off-by: David Ahern <dsahern@gmail.com>
> 
> ---
> 
> diff --git a/vl.c b/vl.c
> index fcf8532..bd3709c 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -152,6 +152,7 @@ int main(int argc, char **argv)
>  #include "qemu-char.h"
>  #include "cache-utils.h"
>  #include "block.h"
> +#include "block_int.h"
>  #include "dma.h"
>  #include "audio/audio.h"
>  #include "migration.h"
> @@ -2551,7 +2552,8 @@ int drive_init(struct drive_opt *arg, int
> snapshot, void *opaque)
>      if (bdrv_open2(bdrv, file, bdrv_flags, drv) < 0) {
>          fprintf(stderr, "qemu: could not open disk image %s\n",
>                          file);
> -        return -1;
> +        if (bdrv->type != BDRV_TYPE_CDROM)
> +            return -1;

I think Cole's patch here:

  https://bugzilla.redhat.com/show_bug.cgi?id=473154#c15

fixes the same problem? Certainly, it seems to me that any code
requiring the path to be e.g. /dev/cd is doomed and should be fixed as
Cole suggests?

Cheers,
Mark.

(Patch below for convenience)

--- new/qemu/block-raw-posix.c	2009-03-28 15:05:16.000000000 -0400
+++ qemu-kvm-0.10/qemu/block-raw-posix.c	2009-04-06 18:57:50.000000000 -0400
@@ -942,16 +942,21 @@ static int hdev_open(BlockDriverState *b
 
     s->type = FTYPE_FILE;
 #if defined(__linux__)
-    if (strstart(filename, "/dev/cd", NULL)) {
+    if (strstart(filename, "/dev/cd", NULL) ||
+        bs->type == BDRV_TYPE_CDROM) {
         /* open will not fail even if no CD is inserted */
         open_flags |= O_NONBLOCK;
         s->type = FTYPE_CD;
-    } else if (strstart(filename, "/dev/fd", NULL)) {
+    }
+    if (strstart(filename, "/dev/fd", NULL) ||
+        bs->type == BDRV_TYPE_FLOPPY) {
         s->type = FTYPE_FD;
         s->fd_open_flags = open_flags;
         /* open will not fail even if no floppy is inserted */
         open_flags |= O_NONBLOCK;
-    } else if (strstart(filename, "/dev/sg", NULL)) {
+    }
+    if (s->type = FTYPE_FILE &&
+        strstart(filename, "/dev/sg", NULL)) {
         bs->sg = 1;
     }
 #endif