kernel memory checks on boot vs. boot time
dillon at apollo.backplane.com
Sun Mar 27 04:20:54 UTC 2011
In DFly I just changed to code to check one word per 64KB instead of
one word per 4KB, which cuts the time down by a factor of 16. At least
some basic 'is this actually memory' test should probably still be done.
Probing 64G of ram was really annoying before I made that change.
Another solution would be to use a much larger mmu mapping, like a DMAP
style mapping. Iterating the dram isn't going to be fast no matter what
since each test requires a full RAS cycle anyway. I didn't try this
approach but it would be easier to code (treating the page directory
entry as a mapping cache for multiple tests).
Adding programmable bells and whistles would be overkill, and high-end
machines shouldn't require a tunable bypass to boot reasonably anyhow.
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