imx233 CPU has read-only unique ID. how to access it from linux?
I presume you mean the CUSTn fields in on chip OTP?
I just happen to be looking at this right now.
To access some of these registers, in particular the customer programmable ID, requires some special operations - as per section 7.2.1 of the i.MX23 reference manual (rev 1).
There is some support available if you set CONFIG_FSL_OTP and rebuild your kernel.
Note that some functionality (possibly only writing to OTP?) requires change in clock speed and VDDIO voltage, which could do bad things to the running kernel or hardware!
Kean
Oh, I just found this: /sys/uid/otp/id
That other kernel config option is only needed for more advanced access.
Kean