Re: [Qemu-devel] [PATCH v2] Added 'access' option to -drive flag

[Anthony Liguori]

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