If you have read my link to the boot message of both the kernels you might have got the answer for this question. Extraversion is added, both are compiled seperately. But both are using same config files, but one is detecting the pci audio device and the other one is not. did any one faced any problem like this consider A is the kernel which detects and B is the kernel which doesnt detect the audio device I found in the end of boot message of kernel A it detects the PCI audio card as hda_codec: U...

CMIIW, you said: for both kernel, you compiled them using exactly the same 2.6.30 source? if yes, have you tried to differentiate the EXTRAVERSION in those two main Makefiles? AFAIK this is needed so during "make modules_install" there will be 2 new directories under /lib/modules/. Both are linked toward different kernel image. Oh and AFAIK too, better compile the image on separate source directory, or the other workaround is to output the compiled objects file on separate directories. regards...