Re: [Qemu-devel] [PATCH RFC v2 8/8] migration: add migration/dirty-bitmap.c

[Vladimir Sementsov-Ogievskiy]

> > > +
> > > +    blk_mig_reset_dirty_cursor();
> > > +    dirty_phase(f, false);
> > > +
> > > +    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
> > > +        uint8_t flags = DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME |
> > > +                        DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME |
> > > +                        DIRTY_BITMAP_MIG_FLAG_ENABLED;
> > > +
> > > +        qemu_put_byte(f, flags);
> > > +        qemu_put_name(f, bdrv_get_device_name(dbms->bs));
> > > +        qemu_put_name(f, bdrv_dirty_bitmap_name(dbms->bitmap));
> > > +        qemu_put_byte(f, bdrv_dirty_bitmap_enabled(dbms->bitmap));
> > > +    }
> > > +
> > > +    qemu_put_byte(f, DIRTY_BITMAP_MIG_FLAG_EOS);
> > > +
> > > +    DPRINTF("Dirty bitmaps migration completed\n");
> > > +
> > > +    dirty_bitmap_mig_cleanup();
> > > +    return 0;
> > > +}
> > > +
> >
> > I suppose we don't need a flag that distinctly SAYS this is the end 
> > section, since we can tell by omission of 
> > DIRTY_BITMAP_MIG_FLAG_NORMAL_CHUNK or ZERO_CHUNK.
> Hmm. I think it simplifies the logic (to use EOS after each section). 
> And the same approach is in migration/block.c.. It's a question about 
> which format is better:  "Each section for dirty_bitmap_load ends with 
> EOS" or "Each section for dirty_bitmap_load ends with EOS except the 
> last one. The last one may be recognized by absent NORMAL_CHUNK and 
> ZERO_CHUNK"

Oh, sorry, no, it's important EOS. There are several blocks with no 
*_CHUNK! Several bitmaps. And loop in dirty_bitmap_load will read them 
iteratively, and it will finish when find EOS.


--
Best regards,
Vladimir