i.MX ProcessorsのトピックRe: imx91 MAC fuse programming in linux shell

imx91 MAC fuse programming in linux shell

Robbi — Wed, 04 Mar 2026 13:41:41 GMT

Hi Team,

I'm able to burn MAC OTP using fuse prog -y command in u-boot terminal. But I need to run a bash script in Linux shell post booting and during that script execution it will ask for user to enter MAC address in command line interface so I had checked OCOTP, which is not available in /sys/bus/nvmem/devices/ (I had enabled NVMEM configurations and OCOTP node in kernel device tree) but I need some guidance or commands to proceed.

Re: imx91 MAC fuse programming in linux shell

joanxie — Thu, 05 Mar 2026 06:38:47 GMT

you can refer to this link

https://community.nxp.com/t5/Security-Blog-NXP-Internal/How-to-fuse-key-through-nvmem-on-i-MX93/ta-p/1657278

Re: imx91 MAC fuse programming in linux shell

Robbi — Thu, 05 Mar 2026 06:41:42 GMT

I'm getting access denied please provide me access.

Re: imx91 MAC fuse programming in linux shell

joanxie — Thu, 05 Mar 2026 09:09:10 GMT

I sent mail to you, pls check

Re: imx91 MAC fuse programming in linux shell

Robbi — Thu, 05 Mar 2026 09:33:34 GMT

Thank for support

Re: imx91 MAC fuse programming in linux shell

Robbi — Fri, 06 Mar 2026 04:15:24 GMT

Hi Team,

As MAC OTP is irreversible process, please verify below command which I'm using to perform MAC OTP.
Note: Our custom board has one ethernet port(i.e. eth1)

Write commands in Uboot terminal:

Consider MAC as 0xAABBCCDDEEFF(6Bytes)

fuse prog -y 39 3 0xCCDDEEFF

fuse prog -y 39 4 0x0000AABB

Read commands in Uboot terminal:

fuse read 39 3

fuse read 39 4

I had referred "i.MX91_Fusemap_RM.xlsx" excel sheet attached to reference manual.
And is there any other source like Reference Manual to confirm the register other than this excel sheet. Waiting for response.

Thank you

Manikanta Robbi

Re: imx91 MAC fuse programming in linux shell

joanxie — Sun, 08 Mar 2026 04:49:01 GMT

the fusemap you refer to is correct, we don't have other fusemap, you can refer to this xlsx files

Re: imx91 MAC fuse programming in linux shell

Robbi — Mon, 09 Mar 2026 09:38:15 GMT

Hi @joanxie

Thanks for the quick response.

I have reviewed the shared "fuse_read_write_test.c" and associated references. However, enabled OCOTP node in kernel device tree and required configuration and modified register bank address and offset in the code but unable to successfully program the MAC address fuse from Linux using the provided source file. Using the above code, I was able to read but not able to the fuse does not update the MAC value in the NVMEM region. Kindly find the attached image for reference.

Is it possible to perform OTP via linux shell(not using u-boot)
if yes, what are the necessary configurations that need to be done to enable write operation.
Share if any references.

Re: imx91 MAC fuse programming in linux shell

joanxie — Fri, 13 Mar 2026 10:42:35 GMT

reading and writing via nvmem is what you need, did you apply the patches I sent to you? do you mean you can read the nvmem correctly, but write failed? any error message?

Re: imx91 MAC fuse programming in linux shell

Robbi — Fri, 13 Mar 2026 10:58:47 GMT

yes joanxie, Thanks for the support I'm using older kernel version (6.6.52) earlier and upgraded to (6.12.46) now the commands are executing successfully.
Thanks for the support

Re: imx91 MAC fuse programming in linux shell

joanxie — Sat, 14 Mar 2026 03:36:55 GMT

great, glad to hear this!

Re: imx91 MAC fuse programming in linux shell

Robbi — Sun, 15 Mar 2026 17:42:49 GMT

Hi @joanxie
I has successfully performed MAC OTP (00:50:F9:27:72:1B) using below commands in linux kernel version-6.12.48

echo -n -e "\x1B\x72\x27\xF9" > /tmp/fuse.bin
dd if=/tmp/fuse.bin of=/sys/bus/nvmem/devices/fsb_s400_fuse1/nvmem bs=4 seek=315 conv=notrunc
echo -n -e "\x50\x00\x00\x00" > /tmp/fuse.bin
dd if=/tmp/fuse.bin of=/sys/bus/nvmem/devices/fsb_s400_fuse1/nvmem bs=4 seek=316 conv=notrunc

verified with reading register using hexdump and fuse read commands.
root@imx:~# hexdump -Cv -s 0x4ec -n 6 /sys/bus/nvmem/devices/fsb_s400_fuse1/nvmem
000004ec 1b 72 27 f9 50 00 |.r'.P.|
000004f2

But I'm not getting fused MAC address while I'm using "ifconfig" command, it is displaying random MAC address.(During boot time also). Please find the attached ZIP file contains ETH kernel device tree node and all relevant images. Guide me to resolve this issue, if I miss enabling any configurations or did I fused correctly registers(Based on Bank and word).

Re: imx91 MAC fuse programming in linux shell

joanxie — Wed, 18 Mar 2026 12:31:22 GMT

sorry there are some issues with community, I missed your message before, do you mind sharing your fuse command result by fuse prog and nvmem dump result?