Re: [XenPPC] xm save/restore tests

[geyi <kudva@xxxxxxxxxxxxxx>]

Jimi Xenidis wrote:
> Thanks Yi,
> On Nov 9, 2006, at 5:22 PM, geyi wrote:
>
> > Jimi,
> >
> > We made several tests on the save/restore with different guest domain 
> > configuration.  Here is the problems we meet in the tests:
> > 1. Cannot get the pfn list on large domain (domain memory >= 1GB). The 
> > xc_get_pfn_list will fail for large domain, because the xemcomm_create 
> > only allocate 1 page for the address mapping table between two 
> > domains. That restricts the pfn_list size transferred in one hcall to 
> > less than 2MB. And in current implementation, we can't transfer the 
> > pfn_list by two hcalls.  So to support the large domain save/restore, 
> > either the getmemlist hcall should be modified to support partially 
> > pfn_list transfer or the xencomm allocate more pages for the address 
> > mapping in an hcall. What's you advice?
> > This is the kernel message we got from domain 0:
> >     xencomm_init: could only translate 2093048 of 2129920 bytes
> >     xencomm_init failure: -28
> This is a known problem, when the dust settles on out next Xen upstream 
> merge (in progress), I hope to have this interface fixed.
> > 2.  We tried to restore a domain with disk root file system. I used 
> > Hao's disk image file for the testing. The restored domain will trap 
> > into Data Access Exception(300). We found that's because the global 
> > pointer "shared" was not NULL before gnttab_resume is called in kernel 
> > resuming. The domain can be restored successfully when we clear the 
> > value of shared  to NULL in gnttab_suspend.
> Hmm, x86 does not check for NULL, it is inserted in the existing address 
> space.
> I think setting it to NULL is a good idea.
> Good catch.
> Can you resend the diff below as a "signed-off" patch to the list?
> > --Yi Ge <kudva@xxxxxxxxxxxxxx>
> > diff -r b03ebb287fa9 drivers/xen/core/gnttab.c
> > --- a/drivers/xen/core/gnttab.c    Fri Nov 03 17:58:22 2006 -0500
> > +++ b/drivers/xen/core/gnttab.c    Thu Nov 09 15:40:35 2006 -0500
> > @@ -426,7 +426,9 @@ int gnttab_suspend(void)
> >  int gnttab_suspend(void)
> >  {
> >  #ifdef CONFIG_PPC_XEN
> > -    return arch_gnttab_suspend(shared);
> > +    int ret =  arch_gnttab_suspend(shared);
> > +    shared = NULL;
> > +    return ret;
> >  #else
> >  #if !defined(__ia64__)
> >      apply_to_page_range(&init_mm, (unsigned long)shared,
> > _______________________________________________
> > Xen-ppc-devel mailing list
> > Xen-ppc-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-ppc-devel
Sure. Please see the attached file below.


--
Yi Ge <kudva@xxxxxxxxxxxxxx>

# HG changeset patch
# User gy@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
# Date 1163170874 18000
# Node ID 714c31abb495ad5800b4b03cf998ca1211f6b36d
# Parent  b03ebb287fa98067dcde1ff7b0bdac3349397ee7
set NULL to shared in gnttab_suspend.

Signed-off-by: Yi Ge <kudva@xxxxxxxxxxxxxx>
Signed-off-by: Dan E Poff <poff@xxxxxxxxxxxxxx>

diff -r b03ebb287fa9 -r 714c31abb495 drivers/xen/core/gnttab.c
--- a/drivers/xen/core/gnttab.c Fri Nov 03 17:58:22 2006 -0500
+++ b/drivers/xen/core/gnttab.c Fri Nov 10 10:01:14 2006 -0500
@@ -426,7 +426,9 @@ int gnttab_suspend(void)
 int gnttab_suspend(void)
 {
 #ifdef CONFIG_PPC_XEN
-       return arch_gnttab_suspend(shared);
+       int ret =  arch_gnttab_suspend(shared);
+       shared = NULL;
+       return ret;
 #else
 #if !defined(__ia64__)
        apply_to_page_range(&init_mm, (unsigned long)shared,

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