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AMBA3 AXI - Exclusive access

1/ What will happen when a master performs 2 exclusive read with 2 different transaction ID to the sam an address location??

Example: Master0 (M0) issue 2 exclusive read with 2 different transaction ID (first is 00 and second is 01) to the sam an address location.

What Master or slave must do in this case??

2/ What will happen when a master performs a exclusive read to an address location,

and then have a transaction read (NOT exclusive read) to that address location??

Parents
  • Hello Yasuhiko Koumoto,

    You told "Anyway, two successive exclusive reads would be illegal and the behavior would be implementation defined."

    I don't understand "two successive exclusive reads would be illegal", that mean two exclusive reads (different address) would be illegal or two exclusive reads (same address) would be illegal??


    How many exclusive read An master can issue in a transaction (with different address/same address; ID can different)??

    Best regards,

    ** Cao Phi

Reply
  • Hello Yasuhiko Koumoto,

    You told "Anyway, two successive exclusive reads would be illegal and the behavior would be implementation defined."

    I don't understand "two successive exclusive reads would be illegal", that mean two exclusive reads (different address) would be illegal or two exclusive reads (same address) would be illegal??


    How many exclusive read An master can issue in a transaction (with different address/same address; ID can different)??

    Best regards,

    ** Cao Phi

Children
  • Hello Cao Phi,

    'illegal' means unusual.

    If an exclusive read has been issued by a master, an exclusive write should be followed.

    This is the normal sequence.

    However, the specification says two successive exclusive reads from the same master are possible.

    In this case, an exclusive monitor in a slave updates the target address for the ID.

    I don't know why the master should do such a thing.

    Best regards.

    Yasuhiko Koumoto.

  • Thank you for your help.

    yasuhikokoumoto wrote:

    Hello Cao Phi,

    'illegal' means unusual.

    If an exclusive read has been issued by a master, an exclusive write should be followed.

    This is the normal sequence.

    However, the specification says two successive exclusive reads from the same master are possible.

    In this case, an exclusive monitor in a slave updates the target address for the ID.

    I don't know why the master should do such a thing.

    Best regards.

    Yasuhiko Koumoto.