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??

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  • Hello,

    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??

    This case would be impossible because transaction ID is defined by an individual master.

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

    From a slave view point, it will act as if two masters exist.

    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??

    A master should issue an exclusive write after issuing an exclusive read. Otherwise, the behaviour would be implementation defined.

    Practically a normal read would not affect an exclusive state.

    Best regards,

    Yasuhiko Koumoto.

  • Hello yasuhikokoumoto

    I have a question. In document on AXI3:

    "In a multimaster system, the interconnect is responsible for appending additional

    information to the ID tag to ensure that ID tags from all masters are unique. The ID tag

    is similar to a master number, but with the extension that each master can implement

    multiple virtual masters within the same port by supplying an ID tag to indicate the

    virtual master number."

    That mean a master can issue multiple transaction with differnt ID.

    Why you tell me that "This case would be impossible because transaction ID is defined by an individual master."??

    Best regards,

    ** Cao Phi

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  • Hello yasuhikokoumoto

    I have a question. In document on AXI3:

    "In a multimaster system, the interconnect is responsible for appending additional

    information to the ID tag to ensure that ID tags from all masters are unique. The ID tag

    is similar to a master number, but with the extension that each master can implement

    multiple virtual masters within the same port by supplying an ID tag to indicate the

    virtual master number."

    That mean a master can issue multiple transaction with differnt ID.

    Why you tell me that "This case would be impossible because transaction ID is defined by an individual master."??

    Best regards,

    ** Cao Phi

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