Re: [PATCH 6/6] hw/ide/piix: Move registration of VMStateDescription to DeviceClass

[BALATON Zoltan]

On Sun, 21 May 2023, Bernhard Beschow wrote:
> The modern, declarative way to set up VM state handling is to assign to
> DeviceClass::vmsd attribute.
>
> There shouldn't be any change in behavior since dc->vmsd causes
> vmstate_register_with_alias_id() to be called on the instance during
> the instance init phase. vmstate_register() was also called during the
> instance init phase which forwards to vmstate_register_with_alias_id()
> internally. Checking the migration schema before and after this patch confirms:
>
> before:
> > qemu-system-x86_64 -S
> > qemu > migrate -d exec:cat>before.mig
>
> after:
> > qemu-system-x86_64 -S
> > qemu > migrate -d exec:cat>after.mig
>
> > analyze-migration.py -d desc -f before.mig > before.json
> > analyze-migration.py -d desc -f after.mig > after.json
> > diff before.json after.json
> -> empty

Missing Signed-off-by line.

Regards,
BALATON Zoltah

> ---
> hw/ide/piix.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/hw/ide/piix.c b/hw/ide/piix.c
> index 47e0b474c3..151f206046 100644
> --- a/hw/ide/piix.c
> +++ b/hw/ide/piix.c
> @@ -28,7 +28,6 @@
>  */
>
> #include "qemu/osdep.h"
> -#include "migration/vmstate.h"
> #include "qapi/error.h"
> #include "hw/pci/pci.h"
> #include "hw/ide/piix.h"
> @@ -159,8 +158,6 @@ static void pci_piix_ide_realize(PCIDevice *dev, Error 
> **errp)
>     bmdma_setup_bar(d);
>     pci_register_bar(dev, 4, PCI_BASE_ADDRESS_SPACE_IO, &d->bmdma_bar);
>
> -    vmstate_register(VMSTATE_IF(dev), 0, &vmstate_ide_pci, d);
> -
>     for (unsigned i = 0; i < 2; i++) {
>         if (!pci_piix_init_bus(d, i, errp)) {
>             return;
> @@ -186,6 +183,7 @@ static void piix3_ide_class_init(ObjectClass *klass, void 
> *data)
>     PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
>
>     dc->reset = piix_ide_reset;
> +    dc->vmsd = &vmstate_ide_pci;
>     k->realize = pci_piix_ide_realize;
>     k->exit = pci_piix_ide_exitfn;
>     k->vendor_id = PCI_VENDOR_ID_INTEL;
> @@ -208,6 +206,7 @@ static void piix4_ide_class_init(ObjectClass *klass, void 
> *data)
>     PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
>
>     dc->reset = piix_ide_reset;
> +    dc->vmsd = &vmstate_ide_pci;
>     k->realize = pci_piix_ide_realize;
>     k->exit = pci_piix_ide_exitfn;
>     k->vendor_id = PCI_VENDOR_ID_INTEL;