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Re: [qemu-s390x] [Qemu-devel] [PATCH 0/3] vfio-ccw: support hsch/csch (k

From: Halil Pasic
Subject: Re: [qemu-s390x] [Qemu-devel] [PATCH 0/3] vfio-ccw: support hsch/csch (kernel part)
Date: Fri, 21 Dec 2018 13:42:22 +0100

On Fri, 21 Dec 2018 12:23:32 +0100
Cornelia Huck <address@hidden> wrote:
> You've really lost me here :( I fear you're criticizing something I
> don't want to implement; I'll write some code, that should make things
> much easier to discuss.


> TBH, I have no idea how this will scale to many vfio-ccw devices.
> > 
> > As long as you return -EAGAIN we are fine. But AFAIU you proposed to
> > do that until the I/O is submitted to the HW subchannel via ssch(). But
> > that is not the case I'm talking about here. We have already translated
> > the channel program for the first request, submitted it via ssch() and
> > are awaiting an interrupt that tells us the I/O is done. While waiting
> > for this interrupt we get a new ssch request. I understood, you don't
> > want to give -EAGAIN for this one, but make the ssch decide. The problem
> > is you still need the old translated channel program for the interrupt
> > handling, and at the same time you need the new channel program
> > translated as well, before doing the ssch for it in the host.
> Why? You're not doing anything with that second ssch at all, it returns
> before translation is started.

OK apparently I misunderstood something -- it was a long and twisty
discussion. Looking forward to the code ;).


> I'll try to post something in January. Have a nice holiday break :)

Don't feel pressured. :) Have nice holidays as well!


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