Re: [Qemu-devel] [PATCH v4 0/5] add CCW indirect data access support

[Cornelia Huck <cornelia.huck@mailbox.org>]

[Restored cc:s]

On Tue, 26 Sep 2017 12:45:11 +0200
Halil Pasic <pasic@linux.vnet.ibm.com> wrote:

> On 09/26/2017 12:18 PM, Cornelia Huck wrote:
> > On Thu, 21 Sep 2017 20:08:36 +0200
> > Halil Pasic <pasic@linux.vnet.ibm.com> wrote:
> >   
> >> Abstract
> >> --------
> >>
> >> The objective of this series is introducing CCW IDA (indirect data
> >> access) support to our virtual channel subsystem implementation. Briefly
> >> CCW IDA can be thought of as a kind of a scatter gather support for a
> >> single CCW. If certain flags are set, the cda is to be interpreted as an
> >> address to a list which in turn holds further addresses designating the
> >> actual data.  Thus the scheme which we are currently using for accessing
> >> CCW payload does not work in general case. Currently there is no
> >> immediate need for proper IDA handling (no use case), but since it IDA is
> >> a non-optional part of the architecture, the only way towards AR
> >> compliance is actually implementing IDA.
> >>
> >> The focus of this patch set is introducing IDA support. There seems to be
> >> a potential for further  improvements based on the introduced
> >> infrastructure, but such improvements are intended to be discusses
> >> separately and realized as patches on top of this series.  
> > 
> > Hm, do you have a list of what you want to do as follow-on patches?
> > (Checking return codes, ...)
> > 
> > It's easy to lose track of all this :)
> >   
> 
> These are the stuff I had in mind:
> * handling errors (aka. checking error codes) in virtio-ccw
> * using residual count
> * converting 3270 (patches already sent)

The 3270 stuff is next in line for me.

> 
> And then some related stuff is the error reporting and handling
> rework for the IO instruction handlers and for the ccw interpretation
> emulation (later affects CcwDataStream).
> 
> There is probably a lot of potential for making things prettier
> in virtio-ccw.c too -- I've done some experiments but ended up changing
> too many things at the same time.

There's always potential for such things :) Let's get the previously
identified stuff out of the door first (it's not that I lack patches to
apply anyway...)

> 
> Btw, do we still have open issues with this series?

Currently going through my acceptance testing.