NXP Semiconductors i.MX 6Dual Reference Manual

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ERR003737Chip Errata for the i.MX 6Dual/6Quad and i.MX 6DualPlus/6QuadPlus, Rev. 6.1, 06/201644 NXP SemiconductorsDescription:The ARM architecture specifies that ARM opcodes of the form 11110 100x001 xxxx xxxx xxxxxxxx xxxx are “Unallocated memory hint (treat as NOP)” if the core supports the MP extensions,as the Cortex-A9 does.The errata is that the Cortex-A9 generates an UNDEFINED exception when bits [15:12] of theinstruction encoding are different from 4’b1111, instead of treating the instruction as a NOP.Projected Impact:Due to the erratum, an unexpected UNDEFINED exception might be generated. In practice, thiserratum is not expected to cause any significant issue, as such instruction encodings are notsupposed to be generated by any compiler, nor used by any handcrafted program.Workarounds:A possible workaround for this erratum is to modify the instruction encoding withbits[15:12]=4.b1111, so that the instruction is truly treated as a NOP by the Cortex-A9.If the instruction encoding cannot be modified, the UNDEFINED exception handler has to copewith this case, and emulate the expected behavior of the instruction, that is, do nothing (NOP),before returning to normal program execution.Proposed Solution:No fix scheduledLinux BSP Status:Software workaround not implemented in Linux BSP. Functionality or mode of operation in whichthe erratum may manifest itself is not used. Software workaround not applicable to the BSP asinstruction encodings are not generated by compiler.ERR003737 ARM: 757119—Some “Unallocated memory hint” instructionsgenerate an UNDEFINED exception instead of being treated as NOP