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

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

[David Ahern]

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;
     }
     if (bdrv_key_required(bdrv))
         autostart = 0;

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

[Mark McLoughlin]

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

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

[David Ahern]

Mark McLoughlin wrote:
> 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?

Cole's patch works as well. I don't have a preference for how it gets
done, just that I can start a guest without checking whether there is
media in the tray and adjusting the qemu invocation.

thanks,

david


> 
> 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
> 
> 
> 

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

[Cole Robinson]

David Ahern wrote:
> 
> Mark McLoughlin wrote:
>> 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?
> 
> Cole's patch works as well. I don't have a preference for how it gets
> done, just that I can start a guest without checking whether there is
> media in the tray and adjusting the qemu invocation.
> 

There is an extra benefit to my patch: /dev/dvd will be treated as a
host cdrom device, so ejecting media in the guest will be mapped to a
physical eject on the host.

I'll touch up my patch and send with a Signed-off-by.

Thanks,
Cole