[PATCH] PPC40x: Limit Allocable RAM During Early Mapping
Grant Erickson
gerickson at nuovations.com
Fri Oct 31 01:33:25 EST 2008
On 10/30/08 7:03 AM, Josh Boyer wrote:
> On Wed, 29 Oct 2008 14:41:14 -0700
> Grant Erickson <gerickson at nuovations.com> wrote:
>> If the size of RAM is not an exact power of two, we may not have
>> covered RAM in its entirety with large 16 and 4 MiB
>> pages. Consequently, restrict the top end of RAM currently allocable
>> by updating '__initial_memory_limit_addr' so that calls to the LMB to
>> allocate PTEs for "tail" coverage with normal-sized pages (or other
>> reasons) do not attempt to allocate outside the allowed range.
>
> Nice catch. I was looking to see if 44x had the same problem, but I
> don't think it does because we simply over-map DRAM there. Does that
> seem correct to you, or am I missing something on 44x that would cause
> this same problem?
Josh,
Because I do not have 44x hardware to validate against and because this
particular fix was localized to the 40x path, I did not take the time to
walk through the 44x path.
Regards,
Grant
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