On 17 March 2013 10:17, Aurelien Jarno <aurel...@aurel32.net> wrote: > On Sun, Mar 17, 2013 at 12:23:31AM +0000, Peter Maydell wrote: >> On 17 March 2013 00:04, Aurelien Jarno <aurel...@aurel32.net> wrote: >> > On Fri, Mar 15, 2013 at 03:45:11PM +0000, Peter Maydell wrote: >> >> I agree we shouldn't be claiming to have a scsi interface, yes. >> >> >> > >> > Does it means you are going to accept the patch? >> >> No, I meant I'd accept a patch which stops us reporting that >> we have a SCSI interface when we don't. > > That's what the patch does, by correctly saying it's an SD interface and > not a SCSI one.
The patch does two things: * stops claiming a default SCSI interface [obviously right] * starts claiming a default SD interface [what we're arguing about] >> > In anycase let me give you some more arguments in favor of it. Even if >> > you believe that users should always provide a cache= argument, I don't >> > think it should be done by setting a wrong default interfaces. Users are >> > likely to simply google for a command line and paste it without >> > understanding the consequences of cache=writeback. The way to go there >> > is to make the writeback argument mandatory for some machines if you >> > really believe it's need by all users. >> >> writeback shouldn't be mandatory randomly for some machines and >> interfaces and not others. > > I don't get your point there. You don't want to make it mandatory at the > QEMU level, but you want users to understand they have to specify it for > some machines, by making if= mandatory randomly for some machines and > not others? My point is that I don't think there's a good solution to "modelled SD cards aren't a good substitute for modelled hard disks". That said, I want to postpone the rest of this conversation until I've had a chance to look into what has changed regarding performance of SD with the default cache settings. -- PMM