[Crash-utility] poisoned per_cpu data not handled on ppc64

[Haren Myneni]

crash-utility-bounces at redhat.com wrote on 03/09/2006 02:01:40 PM:

> Haren Myneni wrote: 
> 
> crash-utility-bounces at redhat.com wrote on 03/09/2006 12:24:26 PM: 
> > Dave Anderson wrote: 
> > 
> > > Sorry -- I see that NR_CPUS is 128 for ppc64 in crash... 
> > > 
> > > But the question remains, do you want to absolutely depend 
> > > upon that always being the case in the kernel? 
> > > 
> > > Dave 
> > 
> > Actually, looking again at the paca code, it doesn't seem that 
> > it is dependent upon the kernel NR_CPUS value. 
> Dave, 
> Since, we are iterating on nr_paca, though that it may not be an 
> issue even if the kernel changed NR_CPUS to < 128. The only issue is
> we are reading NR_CPUS/8 for cpu_online_map - not using the remaining 
part. 
> Probably, it will be more clear if you the cpu_online_map size is 
> based on nr_paca. 
> Like moving the following line  after calculated nr_paca: 
> +        readmem(symbol_value("cpu_online_map"), KVADDR, 
&cpu_online_map[0], 
> +                nr_paca/8, "cpu_online_map", FAULT_ON_ERROR); 
> + 
> Can I go ahead and change it? - drawback of this approach is if the 
> NR_CPUS in the kernel is greater than 128. 
> 
> Well, if NR_CPUS goes above 128 in the kernel, then 
> crash will fail in kernel_init() with: 
> 
>        if (kt->cpus > NR_CPUS) { 
>                error(WARNING, 
>        "calculated number of cpus (%d) greater than compiled-in 
> NR_CPUS (%d)\n", 
>                        kt->cpus, NR_CPUS); 
>                error(FATAL, "recompile crash with larger NR_CPUS\n"); 
>        } 
> so that's not really a problem. 

Dave,

The above error messages will not be printed anyway since the 
ppc64_paca_init will be executed later. At this point, kt->cpus will be 1.

Hence, made minor changes to the previously posted patch.

Thanks
Haren





> 
> or do you prefer actual allocating the online_map based on nr_paca? 
> I will make changes based on your suggestions. 
> 
> I don't care either way -- I just want you guys to be happy.  ;-) 
> So just tell me how you want it, i.e., either keep the patch as is, 
> or send an updated one. 
> Dave 
> 
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