[Crash-utility] Re: [RFC]Patch to accomodate cpu_pda changesinx86_64 kernels

[Dave Anderson]

Badari Pulavarty wrote:

> On Wed, 2006-02-01 at 21:05 +0530, Rachita Kothiyal wrote:
> > On Wed, Feb 01, 2006 at 08:47:07AM -0500, Dave Anderson wrote:
> > >
> > > That should do it.
> > >
> > > Minor nits:  for clarity's sake, I'd make the local variable have the
> > > same name as the kernel symbol it's representing (i.e. _cpu_data
> > > instead of __cpu_data), just check it as a boolean instead of it
> > > being == 1, and increment cpu_pda by sizeof(void *).
> >
> > Hi Dave
> >
> > Incorporating the suggested changes and resending the
> > patch. Kindly review.
> >
> > Thanks
> > Rachita
> >
> > Signed-off-by: Rachita Kothiyal <rachita at in.ibm.com>
> > ---
> >
> >  defs.h   |    9 +++++++
> >  x86_64.c |   77 +++++++++++++++++++++++++++++++++++++++++++++++----------------
> >  2 files changed, 67 insertions(+), 19 deletions(-)
> >
> > diff -puN x86_64.c~crash-fix-cpu-pda x86_64.c
> > --- crash-4.0-2.19/x86_64.c~crash-fix-cpu-pda 2006-02-01 20:08:14.000000000 +0530
> > +++ crash-4.0-2.19-rachita/x86_64.c   2006-02-01 20:59:59.033113672 +0530
> > @@ -365,9 +365,9 @@ x86_64_dump_machdep_table(ulong arg)
> >  static void
> >  x86_64_cpu_pda_init(void)
> >  {
> > -     int i, cpus, nr_pda, cpunumber;
> > +     int i, cpus, nr_pda, cpunumber, _cpu_pda;
> >       char *cpu_pda_buf;
> > -     ulong level4_pgt, data_offset;
> > +     ulong level4_pgt, data_offset, cpu_pda_addr;
> >       struct syment *sp, *nsp;
> >       ulong offset, istacksize;
> >
> > @@ -383,12 +383,26 @@ x86_64_cpu_pda_init(void)
> >
> >       cpu_pda_buf = GETBUF(SIZE(x8664_pda));
> >
> > -     if (!(nr_pda = get_array_length("cpu_pda", NULL, 0)))
> > -             nr_pda = NR_CPUS;
> > +     if (symbol_exists("_cpu_pda")) {
> > +             if (!(nr_pda = get_array_length("_cpu_pda", NULL, 0)))
> > +                     nr_pda = NR_CPUS;
> > +             _cpu_pda = TRUE;
> > +     } else {
> > +             if (!(nr_pda = get_array_length("cpu_pda", NULL, 0)))
> > +                     nr_pda = NR_CPUS;
> > +             _cpu_pda = FALSE;
> > +     }
> >
> >       for (i = cpus = 0; i < nr_pda; i++) {
> > -             if (!CPU_PDA_READ(i, cpu_pda_buf))
> > -                     break;
> > +             if (_cpu_pda) {
> > +                     cpu_pda_addr = 0;
> > +                     if (!_CPU_PDA_READ(i, cpu_pda_buf))
> > +                             break;
>
> Small nit. Why do we initialize "cpu_pda_addr = 0" ? Anyway, it will
> be set by _CPU_PDA_READ() isn't it ? Is it to catch, readmem() failure ?
>
> Thanks,
> Badari

It's unnecessary in all locations, since _CPU_PDA_READ() initializes
its contents with readmem(FAULT_ON_ERROR).  If that happens,
the crash session will abort during initialization.

But, aside from that, this last patch looks good and tests OK on
pre-2.6.16 kernels.

Dave