[Xen-devel] Re: [Crash-utility] xencrash fixes for xen-3.3.0

[Itsuro ODA <oda@xxxxxxxxxxxxx>]

Hi,

It is a good question.
I checked about i386. __per_cpu_data_end - __per_cpu_start is smaller
than 4K, but PERCPU_SHIFT is 13 (it is common both x86_32 and x86_64).
Oops.

I will consider more.

Thanks
Itsuro Oda

On Tue, 07 Oct 2008 09:39:05 -0400
Dave Anderson <anderson@xxxxxxxxxx> wrote:

> Itsuro ODA wrote:
> > Hi,
> > 
> > This patch is for xen hypervisor analysis function of the
> > crash command to apply to the xen-3.3.0 (the newest version of xen).
> > 
> > * PERCPU_SHIFT becomes 13 (from 12) in the xen-3.3.0.
> >   This value is calculated from "__per_cpu_start" and "__per_cpu_data_end".
> > * "jiffies" does not exist in the xen-3.3.0.
> >   It was used to show the uptime. I found there is no altanernative
> >   (i.e. the xen hypervisor does not have the uptime.).
> >   Then if "jiffies" does not exist, "--:--:--" is showed as UPTIME in
> >   the sys command.
> >   (Is it better to eliminate the whole UPTIME line ?)
> >   --- example ---
> >   crash> sys
> >      KERNEL: xen-syms
> >    DUMPFILE: vmcore
> >        CPUS: 4
> >     DOMAINS: 5
> >      UPTIME: --:--:--
> >     MACHINE: Intel(R) Core(TM)2 Quad  CPU   Q9450  @ 2.66GHz  (2660 Mhz)
> >      MEMORY: 2 GB
> >   ----------------
> > 
> > This patch is for crash-4.0-7.2.
> > 
> > Thanks
> > Itsuro Oda
> 
> The patch looks OK.  But just for sanity's sake, is it guaranteed that
> the per_cpu data section will be greater than 4k on both architectures?
> Or could there be some combination of xen CONFIG options that could
> reduce the i386 per_cpu data section contents to less than 4K even though
> PERCPU_SHIFT is 13?
> 
> Dave
> 
> > 
> > ---
> > --- xen_hyper_defs.h.org        2008-10-06 13:45:39.000000000 +0900
> > +++ xen_hyper_defs.h    2008-10-06 13:44:44.000000000 +0900
> > @@ -134,9 +134,8 @@
> >  #endif
> > 
> >  #if defined(X86) || defined(X86_64)
> > -#define XEN_HYPER_PERCPU_SHIFT 12
> >  #define xen_hyper_per_cpu(var, cpu)  \
> > -       ((ulong)(var) + (((ulong)(cpu))<<XEN_HYPER_PERCPU_SHIFT))
> > +       ((ulong)(var) + (((ulong)(cpu))<<xht->percpu_shift))
> >  #elif defined(IA64)
> >  #define xen_hyper_per_cpu(var, cpu)  \
> >         ((xht->flags & XEN_HYPER_SMP) ? \
> > @@ -404,6 +403,7 @@
> >         ulong *cpumask;
> >         uint *cpu_idxs;
> >         ulong *__per_cpu_offset;
> > +       int percpu_shift;
> >  };
> > 
> >  struct xen_hyper_dumpinfo_context {
> > --- xen_hyper.c.org     2008-10-06 13:41:14.000000000 +0900
> > +++ xen_hyper.c 2008-10-06 14:15:03.000000000 +0900
> > @@ -71,6 +71,8 @@
> >  #endif
> > 
> >  #if defined(X86) || defined(X86_64)
> > +       xht->percpu_shift =
> > +           (symbol_value("__per_cpu_data_end") - 
> > symbol_value("__per_cpu_start") > 4096) ? 13: 12;
> >         member_offset = MEMBER_OFFSET("cpuinfo_x86", "x86_model_id");
> >         buf = GETBUF(XEN_HYPER_SIZE(cpuinfo_x86));
> >         if (xen_hyper_test_pcpu_id(XEN_HYPER_CRASHING_CPU())) {
> > @@ -1746,9 +1748,11 @@
> >                         tmp2 = (ulong)jiffies_64;
> >                         jiffies_64 = (ulonglong)(tmp2 - tmp1);
> >                 }
> > -       } else {
> > +       } else if (symbol_exists("jiffies")) {
> >                 get_symbol_data("jiffies", sizeof(long), &jiffies);
> >                 jiffies_64 = (ulonglong)jiffies;
> > +       } else {
> > +               jiffies_64 = 0; /* hypervisor does not have uptime */
> >         }
> > 
> >         return jiffies_64;
> > --- xen_hyper_command.c.org     2008-10-07 08:05:37.000000000 +0900
> > +++ xen_hyper_command.c 2008-10-07 08:24:29.000000000 +0900
> > @@ -1022,7 +1022,8 @@
> >                 (buf1, "%d\n", XEN_HYPER_NR_DOMAINS()));
> >         /* !!!Display a date here if it can be found. */
> >         XEN_HYPER_PRI(fp, len, "UPTIME: ", buf1, flag,
> > -               (buf1, "%s\n", convert_time(xen_hyper_get_uptime_hyper(), 
> > buf2)));
> > +               (buf1, "%s\n", (xen_hyper_get_uptime_hyper() ?
> > +                convert_time(xen_hyper_get_uptime_hyper(), buf2) : 
> > "--:--:--")));
> >         /* !!!Display a version here if it can be found. */
> >         XEN_HYPER_PRI_CONST(fp, len, "MACHINE: ", flag);
> >         if (strlen(uts->machine)) {
> > ---
> 
> 
> 
> 
> --
> Crash-utility mailing list
> Crash-utility@xxxxxxxxxx
> https://www.redhat.com/mailman/listinfo/crash-utility

-- 
Itsuro ODA <oda@xxxxxxxxxxxxx>


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel