[libvirt] [PATCH 0/3] add option to keep nvram file on undefine

[Michal Privoznik]

On 12.09.2016 10:20, Michal Privoznik wrote:
> On 27.05.2016 10:05, Nikolay Shirokovskiy wrote:
>>   There is already a patch [1] on this topic with a different approach - keep
>> nvram file by default. There is also some discussion there. To sum up keeping
>> nvram on undefine could be useful in some usecases so there should be an option
>> to do it. On the other hand there is a danger of leaving domain assets after
>> its undefine and unsing them unintentionally on defining domain with the same
>> name.
>>
>>   AFAIU keeping nvram by default was motivated by domain disks behaviour.
>> I think there is a difference as libvirt never create disks for domain as
>> opposed to nvram and managed save and without disks domain will not start so
>> user is quite aware of disks files. On the other hand one can start using nvram
>> file solely putting <nvram> in config and managed save is created on daemon
>> shutdown. So user is much less aware of nvram and managed save existence. Thus
>> one can easily mess up by unaware define $name/using/undefine/define $name again
>> usecase. Thus I vote for keeping said assets only if it is specified explicitly
>> so user knows what he is doing.
>>
>>   Adding option to undefine is best solution I come up with. The other options
>> are add checks on define or start and both are impossible. Such a check should
>> be done without any extra flags for it to be useful but this way we break
>> existing users.
>>
>>   As this a proof of concept this series does not add extra flag for managed save.
>>
>> [1] https://www.redhat.com/archives/libvir-list/2015-February/msg00915.html
>>
>> Nikolay Shirokovskiy (3):
>>   api: add VIR_DOMAIN_UNDEFINE_KEEP_NVRAM flag
>>   qemu: add VIR_DOMAIN_UNDEFINE_KEEP_NVRAM support
>>   virsh: add --keep-nvram option to undefine command
>>
>>  include/libvirt/libvirt-domain.h |  1 +
>>  src/qemu/qemu_driver.c           | 26 +++++++++++++++++---------
>>  tools/virsh-domain.c             |  8 ++++++++
>>  tools/virsh.pod                  |  6 +++---
>>  4 files changed, 29 insertions(+), 12 deletions(-)
>>
> 
> The patches look good to me (although the commit messages could be a
> little more verbose, e.g. explain why we need to have X and !X flags at
> the same time). I've went trough the discussion you linked and even
> though I usually agree with Dan, this time I think we must not change
> the behaviour of undefine and thus need a special flag for keeping NVRAM.
> 
> ACK, but we might want to give him (or anybody else) chance to chime in,
> so please postpone the push for a while. Thanks!
> 

Okay, this is pushed now. Thank you!

Michal