MMAP fails above 4k size

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http://stackoverflow.com – This is my first post so please let me know if there is any mistake from . My aim is to get approx 150MBytes of data transfer from KERNEL to user space. [This is because i am building an driver for DMA device on OMAP l138 to transfer and receive data between DMA DEVICE and FPGA] Now in LINUX KERNEL i am allocating BUFFER of VARIABLE size using dma_alloc_coherent Then the PHYSICAL address of this buffer i am passing to user space to be user as OFFSET parameter to be used for mmap call from user space . Then from data is copied and read back to and from from user space to kernel This l (HowTos)