*BAD*gran_size in dmesg

On some hardware, with modern RAM sizes you may incur in this kind of messages:

total RAM covered: 32670M
...
 gran_size: 64K 	chunk_size: 4M 	num_reg: 10  	lose cover RAM: 238M
 gran_size: 64K 	chunk_size: 8M 	num_reg: 10  	lose cover RAM: 238M
 gran_size: 64K 	chunk_size: 16M 	num_reg: 10  	lose cover RAM: 238M
*BAD*gran_size: 64K 	chunk_size: 32M 	num_reg: 10  	lose cover RAM: -18M
*BAD*gran_size: 64K 	chunk_size: 64M 	num_reg: 10  	lose cover RAM: -18M
...

To fix this you must specify the parameters at boot time, adding to your grub configuration something like:

enable_mtrr_cleanup mtrr_spare_reg_nr=1 mtrr_gran_size=64K mtrr_chunk_size=16M

You may want to check more info in your kernel documentation mtrr.txt and pat.txt files, and also on these articles:

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