[SLOF] [PATCH] Correctly set ibm,my-drc-index

[David Gibson]

On Sun, 13 Sep 2015 21:25:17 -0500
Michael Roth <mdroth at linux.vnet.ibm.com> wrote:

> Quoting David Gibson (2015-09-13 18:45:00)
> > On Fri, 11 Sep 2015 18:48:19 +0200
> > Laurent Vivier <lvivier at redhat.com> wrote:
> > 
> > > The current calculation of DRC index for PCI card doesn't take
> > > into account the PHB bridge index, so with several bridges we
> > > can have several devices with the same DRC index.
> > > 
> > > This is a problem when we want to unplug a PCI card with
> > > drmgr which is based on the DRC index.
> > > 
> > > Signed-off-by: Laurent Vivier <lvivier at redhat.com>
> > 
> > Actually, I think the safer fix is just for SLOF not to touch the
> > ibm,my-drc-index property if it's already present.  QEMU is already
> > setting it correctly, and SLOF is overwriting it  :(.
> 
> This patch makes sense and fixes a real bug, but my understanding is that
> SLOF only fills in properties missing from device node rather than
> overwriting ones provided by QEMU. On my end, on the second PHB, I see
> this for a hotplugged device in slot 1 (where prop comes from QEMU via
> RTAS):
> 
> mdroth at ubuntu:/proc/device-tree/pci at 800000020000001/pci at 2$ od -x
> ibm,my-drc-index
> 0000000 0140 1000
> 0000004
> 
> And after reboot (where prop comes from QEMU via SLOF):
> 
> mdroth at ubuntu:/proc/device-tree/pci at 800000020000001/ethernet at 2$ od -x
> ibm,my-drc-index
> 0000000 0140 1000
> 0000004
> 
> If you're getting the buggy values (0040 1000, i.e. 40000010 be32 value)
> it makes me think you're not using the QEMU-generated DTs for device
> nodes. Older SLOF that doesn't have Nikunj's updates possibly? I think
> in that case values might get overwritten/thrown out.


Ah.  Good point, yes, the downstream qemu doesn't have the code to set
my-drc-index.

So the question is, do we fix this in SLOF, or do we pull down the qemu
changes to move more device node creation into qemu, making it moot.


> 
> > 
> > Adding Mike Roth to CC, since git blame says he wrote this bit of SLOF
> > code.
> > 
> > >  slof/fs/pci-properties.fs | 3 ++-
> > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/slof/fs/pci-properties.fs b/slof/fs/pci-properties.fs
> > > index 4f13402..d132426 100644
> > > --- a/slof/fs/pci-properties.fs
> > > +++ b/slof/fs/pci-properties.fs
> > > @@ -599,9 +599,10 @@
> > >          pci-reg-props
> > >          pci-hotplug-enabled IF
> > >              \ QEMU uses static assignments for my-drc-index:
> > > -            \ 40000000h + $bus << 8 + $slot << 3
> > > +            \ 40000000h + $phbindex << 16 + $bus << 8 + $slot << 3
> > >              dup dup pci-addr2bus 8 lshift
> > >              swap pci-addr2dev 3 lshift or
> > > +            puid ff and 10 lshift or
> > >              40000000 + encode-int s" ibm,my-drc-index" property
> > >              \ QEMU uses "Slot $bus*32$slotno" for loc-code
> 
> I think loc-code may need to be updated to match QEMU as well.
> 
> > >              dup dup pci-addr2bus 20 *
> > > -- 
> > > 2.1.0
> > > 
> > 
> > 
> > -- 
> > David Gibson <dgibson at redhat.com>
> > Senior Software Engineer, Virtualization, Red Hat
> 


-- 
David Gibson <dgibson at redhat.com>
Senior Software Engineer, Virtualization, Red Hat
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 819 bytes
Desc: OpenPGP digital signature
URL: <http://lists.ozlabs.org/pipermail/slof/attachments/20150914/e15972a5/attachment.sig>