From: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
To: Greg KH <greg@kroah.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
Stephen Rothwell <sfr@canb.auug.org.au>,
linux-next@vger.kernel.org, linux-kernel@vger.kernel.org,
Stefan Hajnoczi <stefanha@gmail.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Anthony Liguori <anthony@codemonkey.ws>,
Zhi Yong Wu <wuzhy@cn.ibm.com>,
David Miller <davem@davemloft.net>,
kvm-devel <kvm@vger.kernel.org>,
target-devel <target-devel@vger.kernel.org>
Subject: Re: linux-next: manual merge of the staging tree with the target-merge tree
Date: Sun, 22 Jul 2012 14:44:23 -0700 [thread overview]
Message-ID: <1342993463.25472.265.camel@haakon2.linux-iscsi.org> (raw)
In-Reply-To: <20120722020746.GB31926@kroah.com>
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
next prev parent reply other threads:[~2012-07-22 21:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-19 4:53 linux-next: manual merge of the staging tree with the target-merge tree Stephen Rothwell
2012-07-19 23:55 ` Greg KH
2012-07-20 17:52 ` Nicholas A. Bellinger
2012-07-20 18:03 ` Greg KH
2012-07-20 18:14 ` Nicholas A. Bellinger
2012-07-20 18:42 ` Michael S. Tsirkin
2012-07-20 23:12 ` Nicholas A. Bellinger
2012-07-22 2:07 ` Greg KH
2012-07-22 21:44 ` Nicholas A. Bellinger [this message]
2012-07-23 15:16 ` Greg KH
2012-07-23 19:47 ` Nicholas A. Bellinger
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