Hi all
Finally I found out the unstable problem about domU boot on ia64.
Please see the comment in patch.
This patch is one solution.
Another solution is to ask the memory attributes to
hypervisor but it looks excessive modification.
Signed-off-by Kouya SHIMURA <kouya@xxxxxxxxxxxxxx>
Best Regards,
Kouya
diff -r b4f1084177cc linux-2.6-xen-sparse/drivers/char/mem.c
--- a/linux-2.6-xen-sparse/drivers/char/mem.c Wed Mar 1 22:06:24 2006
+++ b/linux-2.6-xen-sparse/drivers/char/mem.c Fri Mar 3 19:48:40 2006
@@ -72,10 +72,25 @@
Hopefully a full PAT implementation will fix that soon. */
return 0;
#elif defined(CONFIG_IA64)
+ u64 attr = efi_mem_attributes(addr);
+
+ /*
+ * Physical address is out of EFI memmap. Perhaps Xen
+ * hypervisor passed this address to guest domain via
+ * hypercall and the guest domain freed it and reuse it.
+ *
+ * In this case, this function shouldn't return TRUE.
+ * Because some atomic instructions (cmpxchg, xchg) don't work on
+ * 'UC'(Uncacheable) memory attribute page or virutal aliasing
+ * problem might be occured.
+ */
+ if (attr == 0)
+ return 0;
+
/*
* On ia64, we ignore O_SYNC because we cannot tolerate memory
attribute aliases.
*/
- return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
+ return !(attr & EFI_MEMORY_WB);
#else
/*
* Accessing memory above the top the kernel knows about or through a
file pointer
Magenheimer, Dan (HP Labs Fort Collins) writes:
> Hi all --
>
> We are seeing a strange problem where a recent cset causes
> Red Hat to fail domU boot on ia64 complaining of a hotplug
> problem but doesn't cause any problem for Suse or Debian.
> It is likely some subtle difference (or bug), perhaps in mmap?
> Suggestions/advice from anyone more familiar with distro
> differences (on ia64) would be appreciated.
>
> Changeset is xen-unstable 8783 ("Use /dev/kmem to map dom0
> xenstore page instead of abusing the foreign mapping interface.",
> Feb 8, committed by Christian). Backing out this changeset
> or using the small patch below causes the problem to go away,
> so we have a workaround, but a root cause would be nice
> to know and fix.
>
> Full thread of discussion can be found here:
> http://lists.xensource.com/archives/html/xen-ia64-devel/2006-02/msg00104
> .html
>
> Thanks,
> Dan
>
> > -----Original Message-----
> > From: Akio Takebe [mailto:takebe_akio@xxxxxxxxxxxxxx]
> > Sent: Tuesday, February 28, 2006 2:47 AM
> > To: Magenheimer, Dan (HP Labs Fort Collins); yo.fujita;
> > xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> > Cc: Akio Takebe
> > Subject: RE: [Xen-ia64-devel] Weekly benchmark results [2/3rd week]
> >
> > Hi, Dan
> >
> > I'm still debuging, but it is very difficult...
> > Much advice is welcome. :-)
> >
> > Now I can boot domU by using the following patch.
> >
> > diff -r 6c43118bdba8 tools/xenstore/xenstored_domain.c
> > --- a/tools/xenstore/xenstored_domain.c Fri Feb 24 15:41:08 2006 -0700
> > +++ b/tools/xenstore/xenstored_domain.c Tue Feb 28 18:20:16 2006 +0900
> > @@ -467,6 +467,7 @@ static int dom0_init(void)
> > int rc, fd;
> > evtchn_port_t port;
> > unsigned long kva;
> > + unsigned long mfn;
> > char str[20];
> > struct domain *dom0;
> >
> > @@ -500,9 +501,16 @@ static int dom0_init(void)
> > if (fd == -1)
> > return -1;
> >
> > - dom0->interface = mmap(NULL, getpagesize(),
> > PROT_READ|PROT_WRITE,
> > - MAP_SHARED, fd, kva);
> > - if (dom0->interface == MAP_FAILED)
> > + mfn=((0x0fffffffffffffff & kva) >>14);
> > +/*
> > + dom0->interface = mmap(NULL, getpagesize(),
> > PROT_READ|PROT_WRITE,
> > + MAP_SHARED, fd, kva);
> > +*/
> > + dom0->interface = xc_map_foreign_range(
> > + *xc_handle, 0,
> > + getpagesize(), PROT_READ|PROT_WRITE, mfn);
> > + if (!dom0->interface)
> > +// if (dom0->interface == MAP_FAILED)
> > goto outfd;
> >
> > close(fd);
> >
> > Best Regards,
> >
> > Akio Takebe
> >
> > >Hi Akio --
> > >
> > >Any more progress on this issue? If you are stuck,
> > >maybe we should post the problem to xen-devel to
> > >see if we can get help from a Red Hat person (since
> > >the problem doesn't occur on Suse or Debian).
> > >
> > >Thanks,
> > >Dan
> > >
> > >> -----Original Message-----
> > >> From: Akio Takebe [mailto:takebe_akio@xxxxxxxxxxxxxx]
> > >> Sent: Thursday, February 23, 2006 8:45 PM
> > >> To: Magenheimer, Dan (HP Labs Fort Collins); yo.fujita;
> > >> xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> > >> Cc: Akio Takebe
> > >> Subject: RE: [Xen-ia64-devel] Weekly benchmark results [2/3rd week]
> > >>
> > >> Hi, Dan and Alex
> > >>
> > >> I think this issue is only on ia64.
> > >> I seem that kmem_map@drivers/char/mem.c is used on ia64,
> > >> but mem_map@drivers/xen/char/mem.c is used on x86.
> > >> So I think pfn or kva aren't set correctly.
> > >> We tried to boot domU with revesing cset xen-ia64-ustable.8790
> > >> and it was good work.
> > >>
> > >> I'm still debugging it. :-<
> > >>
> > >> Best Regards,
> > >>
> > >> Akio Takebe
> > >>
> > >> >Confirmed cset xen-unstable 8783 fails while 8782 succeeds.
> > >> >
> > >> >Perhaps there's something different about mmap on RH
> > >> >vs Suse and Debian? Perhaps only on ia64?
> > >> >
> > >>
> > >>
> > >>
> >
> >
> >
>
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