On Sat, 2012-07-21 at 19:07 -0700, Greg KH wrote: > On Fri, Jul 20, 2012 at 09:42:28PM +0300, Michael S. Tsirkin wrote: <SNIP> > > It's very similar to how it was with nouveau: we are not sure > > we can commit to the userspace ABI yet. > > Then you are in trouble :) > I agree with MST here that tcm_vhost needs a clear way to indicate that ABI changes are likely to occur in transmit from staging -> post-staging status. > > Most importantly, it still seems not 100% clear whether this driver will > > have major userspace using it. And if not, it would be very hard to > > support a driver when recent userspace does not use it in the end. > > > > At the moment arguments on upstream mailing list seem to be > > a bit circular: there's no module in upstream kernel so > > userspace does not want to accept the patches. > > > > If we put enabling this driver in staging, then it works out in one of > > two ways > > - userspace starts using it then this effectively freezes the ABI and > > we move it out of staging next release > > - no userspace uses it and we drop it completely or rework ABI > > > > On the other hand, it is marginally better to not want code in staging > > for two reasons: > > - there are dependencies between this code and other code in > > drivers/vhost which are easier for me to handle if it's all > > in one place > > If there are going to be lots of dependancies, then I don't want it in > drivers/staging/ as it doesn't belong there, it belongs cleaned up and > in the "real" place. > > > - a bit easier to track history if we do not move code > > git preserves this, don't worry about that at all. > > So, if this code really does depend on core vhost changes that are going > to be happening over time, I would not recommend it being in > drivers/staging/ as you are right, you are going to have a hard time > syncing with me. > So Linus has merged target-pending/for-next this afternoon, so now we are just waiting on net-next to hit mainline with the vhost patches already ACK'ed by MST. Hopefully that makes things easier for you to considering taking tcm_vhost upstream via staging. ;) Also, MST asked for an RFC-v5 for the initial merge commit with some minor debug wrapper changes that will be going out next week. This will include a move into drivers/staging/tcm_vhost/ against a rebased staging.git patch with the necessary -rc0 mainline dependencies. Please let me know if your OK with this, otherwise I'll just plan to keep -v5 against target-pending/for-next-merge for now, and send a GIT PULL after MST gets back from holiday on the 29th -> 30th. > But don't think that by somehow marking the driver with CONFIG_STAGING > that you get a free pass on the "we are going to break the userspace > api", that's not ok. Be careful about this. Yes, it's tough, and it's > a "chicken and egg" problem like you mention above, I know. > After sleeping on this, I'm wondering if there is not something else we could do at the QEMU level to require an explicit 'development=1' flag in order to use vhost-scsi while tcm_vhost is still marked as staging code..? QEMU folks, would you be open to something like this..? Thank you, --nab -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
