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Re: [Qemu-devel] [PATCH 4/6] libqblock internal used functions
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 4/6] libqblock internal used functions |
Date: |
Tue, 04 Sep 2012 05:38:52 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120828 Thunderbird/15.0 |
On 09/04/2012 01:15 AM, Wenchao Xia wrote:
> δΊ 2012-9-3 23:18, Paolo Bonzini ει:
>> Il 03/09/2012 16:28, Eric Blake 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?
Since qemu does not support it now, yes, you can ignore it for now. But
please make sure that you aren't hard-coding it into the API - that is,
make sure that the API can someday grow to support larger sector sizes
with minimal impact to library clients (that is, that new clients aware
of the new API can target larger sector size once qemu has been patched
to support larger sector size).
--
Eric Blake address@hidden +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- Re: [Qemu-devel] [PATCH 3/6] libqblock error handling, (continued)
- [Qemu-devel] [PATCH 5/6] libqblock test example, Wenchao Xia, 2012/09/03
- [Qemu-devel] [PATCH 4/6] libqblock internal used functions, Wenchao Xia, 2012/09/03
- Re: [Qemu-devel] [PATCH 4/6] libqblock internal used functions, Paolo Bonzini, 2012/09/03
- Re: [Qemu-devel] [PATCH 4/6] libqblock internal used functions, Eric Blake, 2012/09/03
- Re: [Qemu-devel] [PATCH 4/6] libqblock internal used functions, Paolo Bonzini, 2012/09/03
- Re: [Qemu-devel] [PATCH 4/6] libqblock internal used functions, Wenchao Xia, 2012/09/04
- Re: [Qemu-devel] [PATCH 4/6] libqblock internal used functions, Paolo Bonzini, 2012/09/04
- Re: [Qemu-devel] [PATCH 4/6] libqblock internal used functions,
Eric Blake <=
- Re: [Qemu-devel] [PATCH 4/6] libqblock internal used functions, Paolo Bonzini, 2012/09/04
- Re: [Qemu-devel] [PATCH 4/6] libqblock internal used functions, Kevin Wolf, 2012/09/04
- Re: [Qemu-devel] [PATCH 4/6] libqblock internal used functions, Wenchao Xia, 2012/09/10
[Qemu-devel] [PATCH 6/6] libqblock building system, Wenchao Xia, 2012/09/03
[Qemu-devel] [PATCH 2/6] libqblock public type defines, Wenchao Xia, 2012/09/03