Re: [PATCH 0/6] [RFC] Sizing zones and holes in an architecture independent manner

[Luck, Tony]

> That seems to register memory about the 0-2G mark and 6-8G with some small 
> holes here and there. Sounds like what you expected to happen. In case the 
> 1:1 virt->phys mapping is not always true on IA64, I decided to use __pa() 
> instead of PAGE_OFFSET like;
> 
> add_active_range(node, __pa(start) >> PAGE_SHIFT, __pa(end) >> PAGE_SHIFT);
> 
> Is this the correct thing to do or is "start - PAGE_OFFSET" safer? 
> Optimistically assuming __pa() is ok, the following patch (which replaces 
> Patch 5/6 again) should boot (passed compile testing here). If it doesn't, 
> can you send the console log again please?

Almost all of "region 7" (0xE000000000000000-0xFFFFFFFFFFFFFFFF) of the kernel
address space is defined to have a 1:1 mapping with physical memory (the exception
being the top 64K (0xFFFFFFFFFFFF0000-0xFFFFFFFFFFFFFFFF) which is mapped as
a per-cpu area).  So __pa(x) is simply defined as ((x) - PAGE_OFFSET). Using
__pa(start) is effectively identical to (start - PAGE_OFFSET), but __pa() is
a bit cleaner and easier to read.


-Tony
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