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)) {
> > ---
>
>
>
>
> --
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> Crash-utility@xxxxxxxxxx
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--
Itsuro ODA <oda@xxxxxxxxxxxxx>
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