ERR003728
Chip Errata for the i.MX 6Dual/6Quad and i.MX 6DualPlus/6QuadPlus, Rev. 6.1, 06/2016
NXP Semiconductors
31
Description:
Event 0x74 counts the total number of Neon instructions passing through the register rename
pipeline stage. Due to the erratum, the “stall” information is not taken into account. So, one Neon
instruction that remains for n cycles in the register rename stage is counted as n Neon instructions.
As a consequence, the count of event 0x74 might be corrupted, and cannot be relied upon. The
event is also reported externally on PMUEVENT[38:37], which suffers from the same inaccuracy.
Projected Impact:
The implication of this erratum is that Neon instructions cannot be counted reliably in the versions
of the product that are affected by this erratum.
Workarounds:
No workaround is possible to achieve the required functionality of counting how many Neon
instructions are executed (or renamed) in the processor.
Proposed Solution:
No fix scheduled
Linux BSP Status:
Software workaround is not needed because this erratum will not be encountered in normal device
operation. The Freescale Linux BSP does not support this optional profiling feature. Users may add
support for this profiling feature as required, but should ensure the multiple errata impacting the
ARM PMU (Performance Monitoring Unit) are considered especially for multi-core usage.
ERR003728
ARM: 740661—Event 0x74 / PMUEVENT[38:37] may be inaccurate