Everything works as expected without the preempt patch. I'm using cfi_cmdset_0001, jedec_probe, physmap and mtdblock with a 512kByte Intel Flash. But with the patch after 3 to 5 times of copy a file to /dev/mtdblock0 linux userspace stops working. Reading from /dev/mtdblock0 produces after 3 to 5 times a reboot. any hints? Peter