Hi,
I know the docs say CMD26 is reserved and it will not work on SPI mode etc... Obviously some SD manufacturers are not bothered. I don't think it is illegal to write to CID or to exploit the cheaper SD card features provided against the spec.
If no one has used CMD26, then anyone know how to use CMD27? I think CMD26 will also work the same way with required data size.
Thanks,
Harshana