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[Xen-devel] nmi cache weirdness???

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] nmi cache weirdness???
From: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
Date: Thu, 14 Aug 2008 19:20:27 -0700
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This on a 4 CPU AMD box with 64G RAM.

cpu 0 receives ext NMI, calls kdb_nmi() from do_nmi().

asmlinkage void do_nmi(struct cpu_user_regs *regs)
{
    unsigned int cpu = smp_processor_id();
    unsigned char reason;

    ++nmi_count(cpu);

    if ( nmi_callback(regs, cpu) )
        return;

    if ( nmi_watchdog )
        nmi_watchdog_tick(regs);

#ifdef XEN_KDB_CONFIG
       kdb_nmi(TRAP_nmi, regs);
#endif
....
}


kdb_nmi(..):
{
    watchdog_disable();
    set_nmi_callback(kdb_nmi_receive);
    smp_send_nmi_allbutself();
......
}

However, in do_nmi(), nmi_callback still points to dummy (receiving cpus).
What'sinteresting is, if I put two print lines back to back with nothing
in between right at the beginning, then the first prints dummy but the
second prints kdb_nmi_receive. I'm at a complete loss. Does NMI change
cache protocol? I've been looking thru Intel/AMD manuals, but nothing....

Thanks,
Mukesh


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