From: Johannes Berg <johannes@sipsolutions.net>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [RFC] libvhost-user: implement VHOST_USER_PROTOCOL_F_KICK_CALL_MSGS
Date: Fri, 06 Sep 2019 16:48:39 +0200 [thread overview]
Message-ID: <be405c3ba658cdac7f68c91213c3b714ac24c1e3.camel@sipsolutions.net> (raw)
In-Reply-To: <20190906102217-mutt-send-email-mst@kernel.org>
Hi,
On Fri, 2019-09-06 at 10:22 -0400, Michael S. Tsirkin wrote:
> On Fri, Sep 06, 2019 at 03:13:50PM +0300, Johannes Berg wrote:
> > From: Johannes Berg <johannes.berg@intel.com>
> >
> > Signed-off-by: Johannes Berg <johannes.berg@intel.com>
>
> a bit more content here about the motivation for this?
Heh, right, definitely needed.
I was just sending it out as the corresponding patch to the spec change
RFC, where I explained more, so didn't really bother here yet. However,
I evidently forgot to CC you on that:
https://lore.kernel.org/qemu-devel/20190902121233.13382-1-johannes@sipsolutions.net/
I'm still trying to implement it in User-Mode Linux (UML, ARCH=um),
we've submitted patches for virtio/vhost-user support to that, but the
simulation-bound IRQ handling is a bit complicated. I need to see how it
turns out once I actually get it to work - I've gotten this extension,
SLAVE_REQ and REPLY_ACK to work now, so need to "just" integrate with
the time-travel mode I already have.
In any case, if you think that this is a stupid extension and say you
will never accept it, I'll probably just implement a slightly more
hackish way, setting vhost-user to polling mode and using out-of-band
signalling or so. This seems a bit cleaner though, and if it's properly
spec'ed and with sample code and all then it'll possibly be far more
useful to others. (**)
I think I also forgot to CC you on these two:
https://lore.kernel.org/qemu-devel/20190828083401.2342-1-johannes@sipsolutions.net/
https://lore.kernel.org/qemu-devel/20190903192505.10686-1-johannes@sipsolutions.net/
Again, sorry about that.
Btw, at least one of these files doesn't even have an entry in the
maintainers file. Don't remember if it was the spec though or the
libvhost-user stuff.
(**) For example, there's the VMSimInt paper (***) that shows a very
similar thing with QEMU, but works only with CPU emulation. With UML's
time-travel mode made to work over virtio we can do similar things
without CPU emulation. I suspect it's also possible to emulate the HPET
or so in a KVM-based system, but seems far more tricky (to me at least).
(***) http://www.ikr.uni-stuttgart.de/Content/Publications/Archive/We_SIMUTools_2014_40209.pdf
Thanks,
johannes
next prev parent reply other threads:[~2019-09-06 14:49 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-02 12:12 [Qemu-devel] [RFC] vhost-user simulation extension Johannes Berg
2019-09-02 12:12 ` [Qemu-devel] [RFC] docs: vhost-user: add in-band kick/call messages Johannes Berg
2019-09-05 20:28 ` Johannes Berg
2019-09-09 16:00 ` Stefan Hajnoczi
2019-09-09 17:34 ` Johannes Berg
2019-09-10 15:03 ` Stefan Hajnoczi
2019-09-10 15:14 ` Johannes Berg
2019-09-10 15:33 ` Michael S. Tsirkin
2019-09-10 15:34 ` Johannes Berg
2019-09-11 6:56 ` Stefan Hajnoczi
2019-09-11 7:35 ` Stefan Hajnoczi
2019-09-11 8:26 ` Johannes Berg
2019-09-11 15:17 ` Stefan Hajnoczi
2019-09-11 15:31 ` Stefan Hajnoczi
2019-09-11 15:36 ` Johannes Berg
2019-09-11 15:38 ` Johannes Berg
2019-09-12 12:22 ` Stefan Hajnoczi
2019-09-12 20:37 ` Johannes Berg
2019-09-06 12:13 ` [Qemu-devel] [RFC] libvhost-user: implement VHOST_USER_PROTOCOL_F_KICK_CALL_MSGS Johannes Berg
2019-09-06 14:22 ` Michael S. Tsirkin
2019-09-06 14:48 ` Johannes Berg [this message]
2019-09-06 15:12 ` Michael S. Tsirkin
2019-09-06 15:32 ` Johannes Berg
2019-09-08 13:13 ` Michael S. Tsirkin
2019-09-09 11:35 ` Johannes Berg
2019-09-09 12:41 ` Michael S. Tsirkin
2019-09-09 13:05 ` Johannes Berg
2019-09-09 13:48 ` Michael S. Tsirkin
2019-09-09 13:50 ` Johannes Berg
2019-09-09 14:59 ` Michael S. Tsirkin
2019-09-09 15:26 ` Johannes Berg
2019-09-09 15:34 ` Johannes Berg
2019-09-09 15:45 ` Michael S. Tsirkin
2019-09-09 15:47 ` Johannes Berg
2019-09-10 15:52 ` Johannes Berg
2019-09-11 9:16 ` Michael S. Tsirkin
2019-09-11 9:20 ` Johannes Berg
2019-09-11 9:54 ` Michael S. Tsirkin
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