ramcheck kernel module

detect corruption of constant kernel memory (text and data) periodically.
runtime costs about 1..2 ms per sec (10 mb with 5 mb/ms),
which is distributed over 8 (BLOCKS) time partitions (less than half ms per sec).
in case of checksum (xor) error, an kernel log is posted.
manual trigger via /proc/ramcheck is possible.

this new module helps against two scenarios:
1) bit flip on system without crc (typical pc)

more often than you think:
DRAM Errors in the Wild: A Large-Scale Field Study, Mai 2009.
http://www.cs.toronto.edu/~bianca/papers/sigmetrics09.pdf

2) architectures without memory protection.
x86 and x64 using it, but missing (or not enabled) on most other arch.

