Re: [Qemu-stable] [Qemu-devel] [PATCH 1/4] configure: Add --enable-migration-from-qemu-kvm

[Cole Robinson]

On 02/20/2013 03:26 PM, Anthony Liguori wrote:
> Cole Robinson <address@hidden> writes:
> 
>> This switch will turn on all the migration compat bits needed to
>> perform migration from qemu-kvm to qemu. It's just a stub for now.
>>
>> This compat will break incoming migration from qemu < 1.3, but for
>> distros where qemu-kvm was the only shipped package for years it's
>> not a big loss (and I don't know any way to avoid it).
>>
>> Signed-off-by: Cole Robinson <address@hidden>
> 
> This can't be a build time option.  It's ugly and just reintroduces a fork.
> 
> I assume the issue with making it a run time option is that libvirt
> would need to be updated?  Why can't qemu-kvm be a script wrapper that
> passes a fixed flag?
> 

Fedora 18 ships only qemu-kvm-1.2. From that it builds qemu-kvm (with
accel=kvm default) and qemu-system-x86_64 (with accel=tcg default). Both still
have the migration incompatibility issues compared to plain qemu 1.2, like
cirrus mem=16MB.

So even if there was a cli option like -qemu-kvm-compat, in Fedora we would
want to enable it even for both qemu-kvm and qemu-system-x86_64.

Maybe add an option -qemu-kvm-compat=on|off, default to off, but add a
configure option to set default=on? We would set default=on in Fedora, but
users can still manually turn it off.

- Cole


> Regards,
> 
> Anthony Liguori
> 
>> ---
>>  configure | 10 ++++++++++
>>  1 file changed, 10 insertions(+)
>>
>> diff --git a/configure b/configure
>> index bf5970f..296f488 100755
>> --- a/configure
>> +++ b/configure
>> @@ -170,6 +170,7 @@ xfs=""
>>  
>>  vhost_net="no"
>>  kvm="no"
>> +migrate_from_kvm="no"
>>  gprof="no"
>>  debug_tcg="no"
>>  debug="no"
>> @@ -759,6 +760,8 @@ for opt do
>>    ;;
>>    --enable-kvm) kvm="yes"
>>    ;;
>> +  --enable-migration-from-qemu-kvm) migrate_from_kvm="yes"
>> +  ;;
>>    --disable-tcg-interpreter) tcg_interpreter="no"
>>    ;;
>>    --enable-tcg-interpreter) tcg_interpreter="yes"
>> @@ -1087,6 +1090,9 @@ echo "  --enable-bluez           enable bluez stack 
>> connectivity"
>>  echo "  --disable-slirp          disable SLIRP userspace network 
>> connectivity"
>>  echo "  --disable-kvm            disable KVM acceleration support"
>>  echo "  --enable-kvm             enable KVM acceleration support"
>> +echo "  --enable-migration-from-qemu-kvm  Allow migration from qemu-kvm."
>> +echo "                                    This will break migration from "
>> +echo "                                    qemu < 1.3 in most cases"
>>  echo "  --enable-tcg-interpreter enable TCG with bytecode interpreter (TCI)"
>>  echo "  --disable-nptl           disable usermode NPTL support"
>>  echo "  --enable-nptl            enable usermode NPTL support"
>> @@ -3334,6 +3340,7 @@ echo "Linux AIO support $linux_aio"
>>  echo "ATTR/XATTR support $attr"
>>  echo "Install blobs     $blobs"
>>  echo "KVM support       $kvm"
>> +echo "Migrate from qemu-kvm $migrate_from_kvm"
>>  echo "TCG interpreter   $tcg_interpreter"
>>  echo "fdt support       $fdt"
>>  echo "preadv support    $preadv"
>> @@ -3622,6 +3629,9 @@ fi
>>  if test "$signalfd" = "yes" ; then
>>    echo "CONFIG_SIGNALFD=y" >> $config_host_mak
>>  fi
>> +if test "$migrate_from_kvm" = "yes"; then
>> +  echo "CONFIG_MIGRATE_FROM_QEMU_KVM=y" >> $config_host_mak
>> +fi
>>  if test "$tcg_interpreter" = "yes" ; then
>>    echo "CONFIG_TCG_INTERPRETER=y" >> $config_host_mak
>>  fi
>> -- 
>> 1.8.1.2