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AXI 3/AXI 4 Exclusive Access

Sai Karthik Madabhushi
Note: This was originally posted on 14th June 2011 at http://forums.arm.com

Hi,

I have a query  regarding Exclusive Access in AXI 3/ AXI 4. The spec does NOT say anything about this behavior, hence I need a clarification.

1. Can there be two Exclusive Reads monitoring the same address region?

   ARID = 0    ARADDR = 0x004   ARSIZE = 0   ARLEN = 2
   ARID = 3    ARADDR = 0x004   ARSIZE = 1   ARLEN = 1

** Lets assume the above ID's have come sequentially in subsequent cycles and NO exclusive write has come.

2. If YES, then How should the behavior of Exclusive Write be?
a. Exclusive Write of which ID should be entertained?
        b. Should we stop monitoring the OTHER ID when the exclusive write for ONE ID arrives?

3. In case of a successful Exclusive Write, is there a compulsion for the slave to send EXOKAY?
    a. Can it also send SLVERR, or DECERR?

Regards,
Sai Karthik
Parents
  • Note: This was originally posted on 15th June 2011 at http://forums.arm.com

    HI,

    This question is from the perspective of a CHECKER for AXI.
    The Spec says that " The Slave returns an EXOKAY response to the master".
    The thing I want to understand is,

    1. The slave MUST send an EXOKAY response
           OR

        Is there a chance that the slave can also send SLVERR response, due to ANY internal condition.

    2. Is it a protocol violation if the slave sends SLVERR instead of EXOKAY?

    Regards,
    Sai Karthik
Reply
  • Note: This was originally posted on 15th June 2011 at http://forums.arm.com

    HI,

    This question is from the perspective of a CHECKER for AXI.
    The Spec says that " The Slave returns an EXOKAY response to the master".
    The thing I want to understand is,

    1. The slave MUST send an EXOKAY response
           OR

        Is there a chance that the slave can also send SLVERR response, due to ANY internal condition.

    2. Is it a protocol violation if the slave sends SLVERR instead of EXOKAY?

    Regards,
    Sai Karthik
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