[Users] about live snapshot and qemu-kvm

[Gianluca Cecchi]

On Wed, Jan 1, 2014 at 4:38 AM, R P Herrold  wrote:

>
> Out of curiousity, _what_ build environment 'flags' do you
> all, participating in this thread, refer to? -- the thread
> does not enumerate them explicitly, and one cannot expect to
> hit by 'indirect fire', a target not exposed
>
> With best regards, this New Year's eve

I'm far from being a programmer, but as I went to compare build
environments, between
qemu-kvm-rhev-0.12.1.2-2.415.el6_5.3.src.rpm
and
qemu-kvm-0.12.1.2-2.415.el6_5.3.src.rpm
in related spec file I see
[g.cecchi at tekkaman SPECS]$ diff qemu-kvm.spec.upstream qemu-kvm.spec.rhev
3c3
< %define rhev 0
---
> %define rhev 1
12928a12929
> >>>>>>> rhel-6.5

and apart other probably not trivial implications, such as guest agent
part, I see that the "configure" command takes one extra argument in
base RH EL 6.5, that is

--disable-rhev-features

The only patch file containing this keyword is

kvm-Block-streaming-disable-for-RHEL.patch

and inside it there are these lines that impacts configure options and
related built qemu-kvm:

--- a/configure
+++ b/configure
@@ -286,6 +286,7 @@ spice=""
 smartcard=""
 smartcard_nss=""
 live_snapshots="yes"
+block_stream="yes"
 usb_redir=""

 # OS specific
@@ -686,10 +687,22 @@ for opt do
   ;;
   --enable-live-snapshots) live_snapshots="yes"
   ;;
+  --disable-block-stream) block_stream="no"
+  ;;
+  --enable-block-stream) block_stream="yes"
+  ;;
   --disable-usb-redir) usb_redir="no"
   ;;
   --enable-usb-redir) usb_redir="yes"
   ;;
+  --disable-rhev-features)
+       live_snapshots="no";
+       block_stream="no";
+  ;;
+  --enable-rhev-features)
+       live_snapshots="yes";
+       block_stream="yes";
+  ;;
   *) echo "ERROR: unknown option $opt"; show_help="yes"
   ;;
   esac
@@ -863,8 +876,12 @@ echo "  --disable-smartcard-nss  disable
smartcard nss support"
 echo "  --enable-smartcard-nss   enable smartcard nss support"
 echo "  --disable-live-snapshots disable live block device snapshot support"
 echo "  --enable-live-snapshots  enable live block device snapshot support"
+echo "  --disable-block-stream   disable block streaming support"
+echo "  --enable-block-stream    enable block streaming support"
 echo "  --disable-usb-redir      disable usb network redirection support"
 echo "  --enable-usb-redir       enable usb network redirection support"
+echo "  --disable-rhev-features  disable RHEV-only features"
+echo "  --enable-rhev-features   enable RHEV-only features"
 echo ""
 echo "NOTE: The object files are built at the place where configure
is launched"
 exit 1
@@ -2271,6 +2288,7 @@ echo "Trace backend     $trace_backend"
 echo "spice support     $spice"
 echo "nss used          $smartcard_nss"
 echo "Live snapshots    $live_snapshots"
+echo "Block streaming   $block_stream"
 echo "xfsctl support    $xfs"
 echo "usb net redir     $usb_redir"

@@ -2526,6 +2544,10 @@ if test "$live_snapshots" = "yes" ; then
   echo "CONFIG_LIVE_SNAPSHOTS=y" >> $config_host_mak
 fi

+if test "$block_stream" = "yes" ; then
+  echo "CONFIG_BLOCK_STREAM=y" >> $config_host_mak
+fi
+
 if test "$usb_redir" = "yes" ; then
   echo "CONFIG_USB_REDIR=y" >> $config_host_mak
 fi

I don't think the rhev argument has instead implications in upstream
source qemu-kvm-0.12.1.2.tar.gz
So I think that if you want to dig more and if you have more
competences, you have to see the full spec file and the full patch
above.

Files downloaded here:

upstream
http://ftp.redhat.com/redhat/linux/enterprise/6Server/en/os/SRPMS/qemu-kvm-0.12.1.2-2.415.el6_5.3.src.rpm

rhev
http://ftp.redhat.com/redhat/linux/enterprise/6Server/en/RHEV/SRPMS/qemu-kvm-rhev-0.12.1.2-2.415.el6_5.3.src.rpm

Gianluca