??
1) Recommended way is to use CodeWarrior QCVS PBL Tool:
https://www.nxp.com/docs/en/user-guide/QCVS_PBL_User_Guide.pdf
2) You wrote:
> from external DSPI NOR Flash
What do you mean?
> The device will boot from external flash using DSPI interface.
Excuse me, where this interface is shown in the QorIQ LS1043A Reference Manual, Table 4-9. RCW source encodings?
Which changes are required?
> Is it possible to boot from DSPI with LS1023?
All possible boot sources are specified in the QorIQ LS1043A Reference Manual, Table 4-9. RCW source encodings.
The question is not clear.
It is possible to refer to the LS1043ARDB RCW sources at:
https://source.codeaurora.org/external/qoriq/qoriq-components/rcw/tree/ls1043ardb/RR_FQPP_1455?h=LSD...