Re: [PATCH v3 18/21] migration: Make no compression operations into its own structure

[Juan Quintela]

"Dr. David Alan Gilbert" <address@hidden> wrote:
> * Juan Quintela (address@hidden) wrote:
>> It will be used later.
>> 
>> Signed-off-by: Juan Quintela <address@hidden>
>> 

>> +int migrate_multifd_method(void)
>> +{
>> +    MigrationState *s;
>> +
>> +    s = migrate_get_current();
>> +
>> +    return s->parameters.multifd_compress;
>> +}
>
> Shouldn't that be a MultifdCompress enum returned?

You are right here.
>>  
>>  #define MULTIFD_FLAG_SYNC (1 << 0)
>> +#define MULTIFD_FLAG_NOCOMP (1 << 1)
>
> I don't think this should be a set of individual flags; in later patches
> you define a flag for zlib and another for zstd etc etc - but you can't
> combine them - you could never have FLAG_NOCOMP|FLAG_ZSTD|FLAG_ZLIB - so
> this should be a 3 or 4 bit field which contains a compression id (0
> being none).  The ID can't exactly be the migrate_multifd_method() enum
> value - because I don't think that's defined to be stable (?).

The idea is to catch up if we got an incorrect packet with an incorrect
flag.

But yes, I agree that it could be the same expecting a value here.
The problem is that I already have the flags field.

Would it be ok for you if I reserve 3 bits for this?  (right now 2
should be enough).

Thanks, Juan.