Hi

have you done a loop test in serial port (short 2 and 3 pin )
write data in serial port and check are you getting the data in your signal handler .

if it works fine then your program is ok

then go for device .

how frequent you are sending AT command ?

1.Are you able to receive data properly? i mean only receiving data packet from your GPRS device?

i have done a program for my project exactly the same way which you want ?
its working for fine N0 HARDWARE control
see the file attached [file name=serail.txt size=2624]http://www.linux.com/media/kunena/attachments/legacy/files/serail.txt[/file]

Hi

void * kernel_mem = (void *) kmalloc(length_of_heap_vma,GFP_KERNEL);
i think this line is the problem

make void * kernel_mem to char * kernel_mem

it should work . Eagerly waiting for your reply :)