Changes between Version 14 and Version 15 of VirtualMemory


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Timestamp:
Jun 30, 2009, 10:54:06 AM (16 years ago)
Author:
alain
Comment:

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  • VirtualMemory

    v14 v15  
    103103
    104104The generic MMU is implemented as an hardware component in the L1 cache controller.
     105
    105106As the processor core can issue two simultaneous instruction and data requests, there is actually two separated data and instructions caches,
    106107sharing the same physical access to the VCI/OCP interconnect. These cache are set associative, and have a total capacity of 16 Kbytes :
     
    109110 * number of associative ways = 4 ways
    110111
     112The data cache L1 implement a writhe-through policy, in order to simplify the cache-coherence protocol.
     113It contains a write-buffer and that is in charge to build write burst, withe the following constraints :
     114 * the burst length is variable
     115 * the maximal burst length is 8 32 bits words
     116 * all addresses in a burst belongs to the same "half cache line" (32 bytes aligned)
     117 * each adress in a burst can have a different Byte Ebable value (including the 0 value)
     118 
    111119Similarly, the L1 cache controller contains two separated hardware MMUs for instruction and data. Each MMU contains a 64 entries TLB (Translation Look-aside Buffer).
    112120These TLBs are implemented as set-associative caches (16 sets of 4 ways). Each entry in these TLBs can contain either a 4 Kbytes page descriptor, or a 2 Mbytes page descriptor. The figure below illustrate the general structure of the TSAR L1 caches.