Linux not booting consistantly

[Muruga Ganapathy]

I would like to suggest to check the (quality of) clocks to memory
under  

a. normal condition ( before loading the linux)
b. during the linux booting

Usually the clock needs to be buffered if it needs to drive
more memory chips ( banks).

Another suggestion is to increase the cas latency to a higher 
value in the memory controller. ( say from 2 to 2.5 or to a higher
values.

Also there are configuration registers to introduce wait states to 
memory read and write cycles. So you may want to introduce more wait 
states by programming the memory controller register.

Thanks
G.Muruganandam



> I have been working with the hardware guys trying to
> find any issues with the memory, and we haven't seen
> anything yet, and we have talked to AMCC, and they
> said  they couldn't see anything wrong with the
> hardware.  I did do a post-mordum dump of the log
> buffer, and this is what I get:
> 
> 001e40c4: 3c353e4c 696e7578 20766572 73696f6e   
> <5>Linux version
> 001e40d4: 20322e36 2e313520 28726f6f 74406c6f    
> 2.6.15 (root at lo
> 001e40e4: 63616c68 6f73742e 6c6f6361 6c646f6d   
> calhost.localdom
> 001e40f4: 61696e29 20286763 63207665 7273696f    ain)
> (gcc versio
> 001e4104: 6e20342e 302e3020 2844454e 5820454c    n
> 4.0.0 (DENX EL
> 001e4114: 444b2034 2e302034 2e302e30 29292023    DK
> 4.0 4.0.0)) #
> 001e4124: 38205475 65205365 70203236 2031373a    8 Tue
> Sep 26 17:
> 001e4134: 34393a31 33204544 54203230 30360a3c    49:13
> EDT 2006.<
> 001e4144: 343e4a4a 533a2057 41532048 4552454a   
> 4>JJS: WAS HEREJ
> 001e4154: 4a53324a 4a53334a 4a53335f 314a4a53   
> JS2JJS3JJS3_1JJS
> 001e4164: 345f4a4a 53345f31 5f4a4a53 345f325f   
> 4_JJS4_1_JJS4_2_
> 001e4174: 4a4a5334 5f335f4a 4a53345f 00000000   
> JJS4_3_JJS4_....
> 001e4184: 00000000 00000000    ........
> 
> I placed a few printks in arch/ppc/kernel/start.c and
> found that it crashed right after do_init_bootmem(),
> right after placing the first character of "_JJS4_1".
> 
>         printk("JJS3");
>         parse_early_param();
>         printk("JJS3_1");
>         for (i = 0; i < 1000000; i++)
>         {
>                 if (i > 999999)
>                 {
>                         break;
>                 }
>         }
> 
>         printk("JJS4");
>         /* set up the bootmem stuff with available
> memory */
>         do_init_bootmem();
>         printk("_JJS4_1");
>         if ( ppc_md.progress )
> ppc_md.progress("setup_arch: bootmem", 0x3eab);
>         printk("_JJS4_2");
> 
> 
> When it does decide to work, most of the time it gets
> through the whole kernel and everything runs fine,
> though I have seen it hang after probing for PCI
> devices a couple of times.  This looks like it is a
> memory issue, but I don't know what else to try.  Does
> anyone have any ideas?  I would appreciate any input.
> 
> Thanks,
>    Jeff Stevens 
> 
> 
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