Re: [Xen-devel] libxl: cannot start guest

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Christoph Egger wrote:
> On 05/23/12 12:11, Ian Campbell wrote:
>
> > On Tue, 2012-05-22 at 16:32 +0100, Christoph Egger wrote:
> > > On 05/22/12 17:21, Ian Campbell wrote:
> > >
> > > > On Tue, 2012-05-22 at 16:16 +0100, Christoph Egger wrote:
> > > > > On 05/22/12 16:20, Ian Campbell wrote:
> > > > > > All the>= checks on *xcg_handle seem wrong to me. Really they should be
> > > > > > checking != NULL, since otherwise they don't actually discriminate the
> > > > > > two cases! Does making that change help?
> > > > > Yes, that helps! I can start guests again.
> > > > Excellent, I assume you are going to submit the patch (i.e. I don't need
> > > > to..)
> > > Yes, patch attached.
> > I fixed up the commit message as follows. I'll apply if IanJ agrees or
> > acks it.
> Thank you. Ian J. what do you say?
>
> Christoph
>
>
> > 8<-----------------------------
> >
> >  From 6b43ca97f5f8c4fa9bf24101253af21bc66ddf96 Mon Sep 17 00:00:00 2001
> > From: Christoph Egger<Christoph.Egger@xxxxxxx>
> > Date: Tue, 22 May 2012 17:32:21 +0200
> > Subject: [PATCH] xenstore: fix crash on platforms with no gntdev driver 
> > implementation.
> >
> > Fix pointer checks introduced in changeset 24757:aae516b78fce.
> >
> > Signed-off-by: Christoph Egger<Christoph.Egger@xxxxxxx>
> > Acked-by: Ian Campbell<ian.campbell@xxxxxxxxxx>
> > ---
> >   tools/xenstore/xenstored_domain.c |    4 ++--
> >   1 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/xenstore/xenstored_domain.c 
> > b/tools/xenstore/xenstored_domain.c
> > index f8c822f..bf83d58 100644
> > --- a/tools/xenstore/xenstored_domain.c
> > +++ b/tools/xenstore/xenstored_domain.c
> > @@ -167,7 +167,7 @@ static int readchn(struct connection *conn, void *data, 
> > unsigned int len)
> >
> >   static void *map_interface(domid_t domid, unsigned long mfn)
> >   {
> > -       if (*xcg_handle>= 0) {
> > +       if (*xcg_handle != NULL) {
> >                 /* this is the preferred method */
> >                 return xc_gnttab_map_grant_ref(*xcg_handle, domid,
> >                         GNTTAB_RESERVED_XENSTORE, PROT_READ|PROT_WRITE);
> > @@ -179,7 +179,7 @@ static void *map_interface(domid_t domid, unsigned long mfn)
> >
> >   static void unmap_interface(void *interface)
> >   {
> > -       if (*xcg_handle>= 0)
> > +       if (*xcg_handle != NULL)
> >                 xc_gnttab_munmap(*xcg_handle, interface, 1);
> >         else
> >                 munmap(interface, getpagesize());
I also see an error when starting xencommons on NetBSD:

test# /usr/xen42/etc/rc.d/xencommons onestart
Cleaning xenstore database.
Starting xenservices: xenstored, xenconsoled, xenbackendd.xc: error: 
OSDEP: interface 2 (gnttab) not supported on this platform: Internal error
Which is quite annoying, but I'm not really sure of the most elegant way 
to solve this. The error comes from tools/libxc/xc_private.c:177, so 
maybe just removing that message would be ok, or something like this:
--- a/tools/libxc/xc_private.c
+++ b/tools/libxc/xc_private.c
@@ -265,8 +265,12 @@ int xc_evtchn_close(xc_evtchn *xce)
 xc_gnttab *xc_gnttab_open(xentoollog_logger *logger,
                              unsigned open_flags)
 {
+#ifndef __NetBSD__
     return xc_interface_open_common(logger, NULL, open_flags,
                                     XC_OSDEP_GNTTAB);
+#else
+    return NULL;
+#endif
 }

Which is not really pretty.

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