Re: [Qemu-devel] [PATCH 4/6] libqblock internal used functions

[Paolo Bonzini]

Il 04/09/2012 09:15, Wenchao Xia ha scritto:
>>>>> +/* this file contains helper function used internally. */
>>>>> +#define SECTOR_SIZE (512)
>>> Hard-coding this feels wrong, in this day and age of disks with 4096
>>> sectors.  Why isn't this a per-image property?
>>
>> In this day and age of disks with 4096 sectors, Linux does not provide a
>> way to query the required alignment for O_DIRECT...
>>
>> Paolo
>>
> in block.h:
> #define BDRV_SECTOR_BITS   9
> #define BDRV_SECTOR_SIZE   (1ULL << BDRV_SECTOR_BITS)
> #define BDRV_SECTOR_MASK   ~(BDRV_SECTOR_SIZE - 1)
>   it seems block size is always 512 in qemu block layer, so I can
> ignore the 4096 case, do you think so?

Yes.  It is not well supported yet by QEMU, either.

Paolo