Re: [Qemu-devel] [PATCH] hw/vexpress: set default block type to SD

[Aurelien Jarno <aurelien@aurel32.net>]

On Fri, Mar 15, 2013 at 03:35:48PM +0000, Peter Maydell wrote:
> On 5 March 2013 00:44, Aurelien Jarno <aurelien@aurel32.net> wrote:
> > On Tue, Mar 05, 2013 at 08:22:57AM +0800, Peter Maydell wrote:
> >> What effect does this actually have on the user experience?
> >
> > The effect is that the user don't has to specify the interface type.
> > Basically:
> >
> >   -drive file=/path/to/file,if=sd
> > can be replaced by
> >   -drive file=/path/to/file
> >
> > It means the user doesn't have to know the details of the machine to
> > know how to attach a disk. Note that the user here can also be a script,
> > which then becomes a bit simpler.
> 
> I'm not convinced this is a good thing -- I think you should have
> to know that you're attaching an SD card and not a hard disk,
> because the performance is much worse. In particular if you
> don't specify 'cache=writeback' your performance will be
> dreadful, so you need to do something different from hard
> disks anyhow.
> 

Being a good thing or not, the current code is wrong: the default
interface type is set to SCSI (I guess it has been copied from
versatilepb.c), while the vexpress machine has no SCSI 
interface.

-- 
Aurelien Jarno	                        GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net