Re: [PATCH v2 3/5] ramfb: implement migration support

[Laszlo Ersek]

On 10/2/23 14:01, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Oct 2, 2023 at 3:12 PM <marcandre.lureau@redhat.com> wrote:
>>
>> From: Marc-André Lureau <marcandre.lureau@redhat.com>
>>
>> Implementing RAMFB migration is quite straightforward. One caveat is to
>> treat the whole RAMFBCfg as a blob, since that's what is exposed to the
>> guest directly. This avoid having to fiddle with endianness issues if we
>> were to migrate fields individually as integers.
>>
>> The following patches turns the migration only on machine >= 8.2.
>>
>> Fixes:
>> https://bugzilla.redhat.com/show_bug.cgi?id=1859424
>>
>> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
>> ---
>>  hw/display/ramfb.c | 21 +++++++++++++++++++++
>>  1 file changed, 21 insertions(+)
>>
>> diff --git a/hw/display/ramfb.c b/hw/display/ramfb.c
>> index 79b9754a58..4aaaa7d653 100644
>> --- a/hw/display/ramfb.c
>> +++ b/hw/display/ramfb.c
>> @@ -12,6 +12,7 @@
>>   */
>>
>>  #include "qemu/osdep.h"
>> +#include "migration/vmstate.h"
>>  #include "qapi/error.h"
>>  #include "hw/loader.h"
>>  #include "hw/display/ramfb.h"
>> @@ -28,6 +29,8 @@ struct QEMU_PACKED RAMFBCfg {
>>      uint32_t stride;
>>  };
>>
>> +typedef struct RAMFBCfg RAMFBCfg;
>> +
>>  struct RAMFBState {
>>      DisplaySurface *ds;
>>      uint32_t width, height;
>> @@ -115,6 +118,23 @@ void ramfb_display_update(QemuConsole *con, RAMFBState 
>> *s)
>>      dpy_gfx_update_full(con);
>>  }
>>
>> +static int ramfb_post_load(void *opaque, int version_id)
>> +{
>> +    ramfb_fw_cfg_write(opaque, 0, 0);
>> +    return 0;
>> +}
>> +
>> +static const VMStateDescription vmstate_ramfb = {
>> +    .name = "ramfb",
>> +    .version_id = 1,
>> +    .minimum_version_id = 1,
>> +    .post_load = ramfb_post_load,
>> +    .fields = (VMStateField[]) {
>> +        VMSTATE_BUFFER_UNSAFE(cfg, RAMFBState, 0, sizeof(RAMFBCfg)),
>> +        VMSTATE_END_OF_LIST()
>> +    }
>> +};
>> +
>>  RAMFBState *ramfb_setup(Error **errp)
>>  {
>>      FWCfgState *fw_cfg = fw_cfg_find();
>> @@ -127,6 +147,7 @@ RAMFBState *ramfb_setup(Error **errp)
>>
>>      s = g_new0(RAMFBState, 1);
>>
>> +    vmstate_register(NULL, 0, &vmstate_ramfb, s);
> 
> wip:
> I am going to make it attached to the actual device.

I'm really curious about that -- I think it's going to be better, and
it'll teach me stuff about migration!

Laszlo