Re: [PATCH V5 00/19] Live update: cpr-exec

["Cédric Le Goater" <clg@redhat.com>]

On 10/1/25 21:24, Steven Sistare wrote:
> On 10/1/2025 3:07 PM, Steven Sistare wrote:
>> On 10/1/2025 2:56 PM, Peter Xu wrote:
>>> On Wed, Oct 01, 2025 at 08:33:52AM -0700, Steve Sistare wrote:
>>>> This patch series adds the live migration cpr-exec mode.
>>>>
>>>> The new user-visible interfaces are:
>>>>    * cpr-exec (MigMode migration parameter)
>>>>    * cpr-exec-command (migration parameter)
>>>>
>>>> cpr-exec mode is similar in most respects to cpr-transfer mode, with the
>>>> primary difference being that old QEMU directly exec's new QEMU.  The user
>>>> specifies the command to exec new QEMU in the migration parameter
>>>> cpr-exec-command.
>>>
>>> It turns out I was right where I replied to patch 5; this fails the Windows
>>> build.
>>>
>>> Smallest fix is to wrap qemu_memfd_create() with a CONFIG_LINUX ifdef,
>>> returning -1 to mfd otherwise.
>>
>> That does not make sense.  It already does that, which is why I used it:
>>
>> util/memfd.c
>>
>> int qemu_memfd_create(const char *name, size_t size, bool hugetlb,
>>                        uint64_t hugetlbsize, unsigned int seals, Error **errp)
>> {
>>      ...
>> #ifdef CONFIG_LINUX
>>      ...
>>      return mfd;
>> #else
>>      error_setg_errno(errp, ENOSYS, "failed to create memfd");
>> #endif
>>      return -1;
>> }
>>
>> Did the windows build fail due to a different error?
>>
>>> A better one is we only include cpr*.c in meson.build if it's linux.
>>> Personally I'm OK if we go with the smaller one as of now, however then it
>>> would definitely be nice to have a follow up series to reach the better
>>> solution, if that makes sense.
>>>
>>> Feel free to use "make docker-test-build@fedora-win64-cross" for verifying
>>> the changes.  I hope it'll work for you, even if for me currently it didn't
>>> work due to a gitlab.com dns resolution pulling dtc src, where I didn't dig
>>> deeper yet..
>>>
>>> The other thing is, this series doesn't apply on master branch.  I didn't
>>> feel confident to do it myself on the vfio change, please have a look on
>>> both issues.
>> Ugh, they renamed everything.  I will rebase and send V6.
> 
> Actually that was easy to resolve, not worth a V6?
> 
> In patch "vfio: cpr-exec mode", drop the change in container.c, and instead
> add MIG_MODE_CPR_EXEC to container-legacy.c here:
> 
>          if (migrate_add_blocker_modes(&vbasedev->cpr.mdev_blocker, errp,
>                                        MIG_MODE_CPR_TRANSFER, MIG_MODE_CPR_EXEC,
>                                        -1) < 0) {
yes.

Thanks,

C.