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Altera_Forum's avatar
Altera_Forum
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16 years ago

In the "creating multiprocessor Nios II systems",I have found a problem on mailbox

Hi,:p

In the tuturial,the shared memory is 4KBytes .The mailbox's offset is 0x800 which I think is at the middle of the shared memory and the size of the mailbox is 0x100. So does this mean that the mailbox is located in the middle of the shared memory? Why should we do this ? Why don't we just put the mailbox at the beginning or the end of the shared memory? Why do we partition the memory?:confused:

Does anybody know the answer? Thank you so much....:rolleyes: :D

5 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Does anybody know the answer?Is my understanding the of mailbox wrong?

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    I didn't have a look at the software part of the tutorial, but you are free to use the location that you want in the shared memory. Maybe they want to use the first 2k to store some other data...

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    --- Quote Start ---

    I didn't have a look at the software part of the tutorial, but you are free to use the location that you want in the shared memory. Maybe they want to use the first 2k to store some other data...

    --- Quote End ---

    Hi,thank you for your reply.But I think the first 2k is just used as the shared memory which woul store the message between the 2 processors.What I feel confused is that why they partition the shared memory in this way:

    first 2 K :shared memory;

    second 1K:mailbox;

    third 1K :shared memory.
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    It's a good question... but it isn't best or worse than any other solution. As long as you are using an offset inside the shared memory it will work.

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    --- Quote Start ---

    It's a good question... but it isn't best or worse than any other solution. As long as you are using an offset inside the shared memory it will work.

    --- Quote End ---

    OK.Thanks.It is only a little strange