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Re: [Qemu-ppc] [PATCH v6 07/15] spapr_rtas: add ibm, configure-connector
From: |
David Gibson |
Subject: |
Re: [Qemu-ppc] [PATCH v6 07/15] spapr_rtas: add ibm, configure-connector RTAS interface |
Date: |
Tue, 3 Mar 2015 16:33:39 +1100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Mon, Mar 02, 2015 at 10:40:16PM -0600, Michael Roth wrote:
> Quoting David Gibson (2015-03-02 01:02:46)
> > On Thu, Feb 26, 2015 at 09:11:07PM -0600, Michael Roth wrote:
> > > This interface is used to fetch an OF device-tree nodes that describes a
> > > newly-attached device to guest. It is called multiple times to walk the
> > > device-tree node and fetch individual properties into a 'workarea'/buffer
> > > provided by the guest.
> > >
> > > The device-tree is generated by QEMU and passed to an sPAPRDRConnector
> > > during
> > > the initial hotplug operation, and the state of these RTAS calls is
> > > tracked by
> > > the sPAPRDRConnector. When the last of these properties is successfully
> > > fetched, we report as special return value to the guest and transition
> > > the device to a 'configured' state on the QEMU/DRC side.
> > >
> > > See docs/specs/ppc-spapr-hotplug.txt for a complete description of
> > > this interface.
> > >
> > > Signed-off-by: Michael Roth <address@hidden>
> >
> >
> > So, actually, here's probably the best place to explain what I had in
> > mind for changing the internal interface for this stuff. I was
> > thinking something like this pseudocode:
> >
> > struct DRCCCState {
> > void *fdt;
> > int offset;
> > int depth;
> > };
> >
> > rtas_configure_connector()
> > {
> > ...
> > DRCCCState *ccstate;
> > ...
> >
> > /* check parameters, retrieve drc */
> > ccstate = drc->ccstate;
> >
> > if (!ccstate) {
> > /* Haven't started configuring yet */
> > ccstate = malloc(...);
> > /* Retrieve the dt fragment from the backend */
> > ccstate->fdt = drck->get_dt(...);
> > ccstate->offset = 0;
> > }
> >
> > while (get next tag from fdt) {
> > switch (tag)
> > case FDT_PROPERTY:
> > /* Translate property into rtas return values */
> > return SPAPR_DR_CC_RESPONSE_NEXT_PROPERTY;
> >
> > /* other cases ... */
> > }
> >
> > /* Fall through only if we've completed streaming out the dt
> > */
> >
> > /* Tell the back end we've finished configuring */
> > drck->cc_completed(...);
> > return SPAPR_DR_CC_RESPONSE_SUCCESS;
> > }
> >
> > On reset, or anything else which interrupts the configuration process,
> > just blow away drc->ccstate.
>
> Ok, that seems reasonable. I took a stab at it here:
>
>
> https://github.com/mdroth/qemu/commit/79ce372743da1b63a6fa33e3de1f1daba8ea1fdc
> https://github.com/mdroth/qemu/commits/spapr-hotplug-pci
It's looking pretty close now, thanks for the rework.
> It exposes the ccstate as you suggested, via drck->get_cc_state(), and in
> place of drck->cc_completed() I have drck->set_configured() which serves
> roughly the same purpose I think. I opted not to let RTAS handle
> allocation, since it seemed to imply RTAS owns it and not the DRC.
So, that was intentional; basically RTAS *does* own the CCstate. But
for convenience of index we need connect it to the DRC. Think of it
like an rtas_priv field in the DRC.
In particular I think the CCstate should be opaque to everything
except the RTAS code itself, which means initializing the offset and
depth in RTAS, not in a drck callback. As far as the drck callback
is concerned, it's supplying a dt fragment, but it doesn't care about
the details of how the upper layer communicates that through to the
guest.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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- Re: [Qemu-ppc] [PATCH v6 07/15] spapr_rtas: add ibm, configure-connector RTAS interface, David Gibson, 2015/03/02
- Re: [Qemu-ppc] [PATCH v6 07/15] spapr_rtas: add ibm, configure-connector RTAS interface, Michael Roth, 2015/03/02
- Re: [Qemu-ppc] [PATCH v6 07/15] spapr_rtas: add ibm, configure-connector RTAS interface,
David Gibson <=
- Re: [Qemu-ppc] [PATCH v6 07/15] spapr_rtas: add ibm, configure-connector RTAS interface, Michael Roth, 2015/03/04
- Re: [Qemu-ppc] [PATCH v6 07/15] spapr_rtas: add ibm, configure-connector RTAS interface, Michael Roth, 2015/03/04
- Re: [Qemu-ppc] [PATCH v6 07/15] spapr_rtas: add ibm, configure-connector RTAS interface, David Gibson, 2015/03/05
- Re: [Qemu-ppc] [PATCH v6 07/15] spapr_rtas: add ibm, configure-connector RTAS interface, Michael Roth, 2015/03/05
- Re: [Qemu-ppc] [PATCH v6 07/15] spapr_rtas: add ibm, configure-connector RTAS interface, David Gibson, 2015/03/12
- Re: [Qemu-ppc] [PATCH v6 07/15] spapr_rtas: add ibm, configure-connector RTAS interface, Michael Roth, 2015/03/16
- Re: [Qemu-ppc] [PATCH v6 07/15] spapr_rtas: add ibm, configure-connector RTAS interface, David Gibson, 2015/03/22