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Re: [Qemu-devel] Question about block driver


From: Wen Congyang
Subject: Re: [Qemu-devel] Question about block driver
Date: Thu, 30 Apr 2015 17:43:16 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0

On 04/30/2015 05:33 PM, Kevin Wolf wrote:
> [Cc: qemu-block]
> 
> Am 30.04.2015 um 11:11 hat Wen Congyang geschrieben:
>> Some drivers use bdrv_open, while the other dirvers use bdrv_file_open().
>> What is the difference between bdrv_open() and bdrv_file_open()?
> 
> bdrv_file_open() is used by protocol drivers that don't need any other
> driver to work (e.g. raw-posix), bdrv_open() is used by format drivers
> that need a bs->file (e.g. raw or qcow2).
> 
> They used to have different parameters originally, but nowadays that's
> the only difference.

So, if the driver wants to open bs->file itself, it should use bdrv_file_open(),
and the driver wants bs->file has already been opened before its open, it should
use bdrv_open(). Is it right?

Thanks
Wen Congyang

> 
> Kevin
> .
> 




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