EciAdsl driver is compatible with 2.6 kernels since version 0.9.
All 2.6 kernels between 2.6.0 and 2.6.6 have to be patched (look at link below).
Update on 2004-06-23: 2.6.7 and 184.108.40.206 kernels are not stable with EciAdsl.
Kernel 2.6.9-rc1 seems stable.
Feel free to report us any stability problem with 2.6 kernels.
• Patch for 2.6 kernels (≥ 2.6.0 and ≤ 2.6.6)
If you want to use an old kernel, you should edit the patch to adjust it to that version, then apply it and recompile the kernel. After you have to build an initrd image by using mkinitrd.