Im making my very first Linux driver at the moment, it's a Host driver to a custom made SD/MMC card

controller for opencores.org.

I wonder if someone has experience in writing those kind of host drivers, or blockdrivers in general?

Because i encounter some problems that i hope some one can give some advice on. Without no debug tool except

printk the debugging is tedious.

1) After the card initialization process,i got the following printout from the system:
mmc: new SD card at address 0002
mmcblk0 : mmc:0002 ???????????????????????????????????? 2129587936 KiB.
The print oblivious not correct in hex its (EFBF BDEF BFBD EFBF BDEF BFBD EFBF). The address output i was

able to track to the bus.c, but were does the "mmcblk0 : " line comes from?