Libguestfs - Apr 2016 - Re: [PATCH] launch: direct: specify format for appliance drive

The drive used for the appliance is a raw (sparse) disk: specify that
explicitly in its -drive qemu command line options, so qemu can skip the
autodetection of its format and save a tiny bit of time.
---
 src/launch-direct.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/launch-direct.c b/src/launch-direct.c
index ee0a855..8521e5a 100644
--- a/src/launch-direct.c
+++ b/src/launch-direct.c
@@ -563,7 +563,7 @@ launch_direct (guestfs_h *g, void *datav, const char *arg)
   /* Add the ext2 appliance drive (after all the drives). */
   if (has_appliance_drive) {
     ADD_CMDLINE ("-drive");
-    ADD_CMDLINE_PRINTF
("file=%s,snapshot=on,id=appliance,cache=unsafe,if=none",
+    ADD_CMDLINE_PRINTF
("file=%s,snapshot=on,id=appliance,cache=unsafe,if=none,format=raw",
                         appliance);
 
     if (virtio_scsi) {
-- 
2.5.5

On Mon, Apr 18, 2016 at 02:49:07PM +0200, Pino Toscano
wrote:
> The drive used for the appliance is a raw (sparse) disk: specify that
> explicitly in its -drive qemu command line options, so qemu can skip the
> autodetection of its format and save a tiny bit of time.
> ---
>  src/launch-direct.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/launch-direct.c b/src/launch-direct.c
> index ee0a855..8521e5a 100644
> --- a/src/launch-direct.c
> +++ b/src/launch-direct.c
> @@ -563,7 +563,7 @@ launch_direct (guestfs_h *g, void *datav, const char
*arg)
>    /* Add the ext2 appliance drive (after all the drives). */
>    if (has_appliance_drive) {
>      ADD_CMDLINE ("-drive");
> -    ADD_CMDLINE_PRINTF
("file=%s,snapshot=on,id=appliance,cache=unsafe,if=none",
> +    ADD_CMDLINE_PRINTF
("file=%s,snapshot=on,id=appliance,cache=unsafe,if=none,format=raw",
>                          appliance);
ACK.

If I'm right, it seems we don't need any change in
src/launch-libvirt.c, because we specify the backing file format
("raw") when creating the overlay in make_qcow2_overlay, and we set
the overlay format ("qcow2") when adding the disk XML in
construct_libvirt_xml_appliance.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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bindings from many languages.  http://libguestfs.org

On Monday 18 April 2016 17:49:22 Richard W.M. Jones
wrote:
> On Mon, Apr 18, 2016 at 02:49:07PM +0200, Pino Toscano wrote:
> > The drive used for the appliance is a raw (sparse) disk: specify that
> > explicitly in its -drive qemu command line options, so qemu can skip
the
> > autodetection of its format and save a tiny bit of time.
> > ---
> >  src/launch-direct.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/src/launch-direct.c b/src/launch-direct.c
> > index ee0a855..8521e5a 100644
> > --- a/src/launch-direct.c
> > +++ b/src/launch-direct.c
> > @@ -563,7 +563,7 @@ launch_direct (guestfs_h *g, void *datav, const
char *arg)
> >    /* Add the ext2 appliance drive (after all the drives). */
> >    if (has_appliance_drive) {
> >      ADD_CMDLINE ("-drive");
> > -    ADD_CMDLINE_PRINTF
("file=%s,snapshot=on,id=appliance,cache=unsafe,if=none",
> > +    ADD_CMDLINE_PRINTF
("file=%s,snapshot=on,id=appliance,cache=unsafe,if=none,format=raw",
> >                          appliance);
> 
> ACK.
> 
> If I'm right, it seems we don't need any change in
> src/launch-libvirt.c, because we specify the backing file format
> ("raw") when creating the overlay in make_qcow2_overlay, and we
set
> the overlay format ("qcow2") when adding the disk XML in
> construct_libvirt_xml_appliance.
Yup, that's why only the direct backend was patched.

-- 
Pino Toscano