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Date: Thu, 07 Jan 2010 13:59:47 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [PATCH v2] Added 'access' option to -drive flag
References: <4B338293.4000306@redhat.com>
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To: Naphtali Sprei <nsprei@redhat.com>
Cc: qemu-devel@nongnu.org

On 12/24/2009 09:02 AM, Naphtali Sprei wrote:
> The new option is: access=[rw|ro|auto]
> rw: open the drive's file with Read and Write permission, don't continue if failed
> ro: open the file only with Read permission
> auto: open the file with Read and Write permission, if failed, try only Read permision
>
> For compatibility reasons, the default is 'auto'. Should be changed later on.
>
> This option replaces the 'readonly' options added lately.
>
> Instead of using the field 'readonly' of the BlockDriverState struct for passing the request,
> pass the request in the flags parameter to the function.
>
> The BDRV_O_RDWR/RDONLY becomes just one bit, BDRV_O_RDONLY gone.
>    

Users shouldn't be involved in deciding how an image is open.

Instead, marking a drive read only (via readonly) should cause a file to 
be open read-only.  By default, when media=cdrom, we should toggle the 
readonly flag.

As for the behaviour with trying read-write and then read-only, let's 
just drop it.  It's a bug and I've seen it reported half a dozen times 
as such.

Regards,

Anthony Liguori