Re: [Qemu-devel] format=raw,readonly errors

["Daniel P. Berrange" <berrange@redhat.com>]

On Mon, May 08, 2017 at 11:32:12AM -0400, John Snow wrote:
> 
> 
> On 05/08/2017 10:15 AM, Carl Karsten wrote:
> > On Mon, May 8, 2017 at 3:51 AM, Markus Armbruster <armbru@redhat.com> wrote:
> > 
> >> Carl Karsten <carl@personnelware.com> writes:
> >>
> >>> juser@gator:~/temp$ qemu-system-x86_64 -m 256 -display curses  -drive
> >>> file=disk.cow -drive file=boot.img
> >>> WARNING: Image format was not specified for 'boot.img' and probing
> >> guessed
> >>> raw.
> >>>          Automatically detecting the format is dangerous for raw images,
> >>> write operations on block 0 will be restricted.
> >>>          Specify the 'raw' format explicitly to remove the restrictions.
> >>>
> >>> This is OK, as I don't want anything writing to that thing anyway.  So to
> >>> get rid of the waring:
> >>>
> >>> juser@gator:~/temp$ qemu-system-x86_64 -drive
> >>> file=boot.img,format=raw,readonly qemu-system-x86_64: Can't use a
> >> read-only
> >>> drive
> >>> qemu-system-x86_64: Initialization of device ide-hd failed: Device
> >>> initialization failed.
> >>
> >> -drive without if=... creates an IDE disk[*].  IDE disks can't do
> >> read-only.  Have you tried omitting ",readonly"?
> >>
> > 
> > 
> > omitting works, but my goal was for the drive to be read only.
> > 
> > 
> 
> I don't think there's a way to make physical IDE drives "read only." I
> don't think there's any jumper settings or any of the like which can
> accomplish this.

You could use an IDE cdrom though, rather than an IDE disk, as that's
readonly from guest POV (we don't emulate a cd-writer).

Regards,
Daniel
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