[GSoC] BAT vs Pages on PowerPC [Please give a feedback]

[Thomas Doerfler]

Chris,

Am 23.06.2013 03:46, schrieb Chris Johns:
> Thomas Dörfler wrote:
>>
> 
>> Note that the pages usually only cover 4K of
>> memory, and the "translation lookaside buffer" (TLB) only maintains the
>> last 16-64 used pages,
> 
> The ARM which I am currently using and have handy seems to support 1MB,
> 64K and 4K ranges depending on the TLB table level used. I would be
> surprised if an entry was needed for each page in use.

Classic PowerPC ist not that flexible. The 603(e) core, that is quite
often used in PPC controllers, has a fixed page table entry size of 4K,
so the number of TLB entries (the "page cache") will never cover the
whole lot of pages for a suitable memory size.

So for this derivative (and many others) it's "Use (statically
initialized) BATs or (dynamically reloaded) TLB entries".

Thomas.

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