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about copy_to_user

Shinji1
Intellectual 380 points

Is it possible to change from 32-bit to 16-bit access the "copyt_to_user"?

I'm developing a Linux driver that read/write to fpga.
(fpga has been connected by a 16-bit bus.fpga is 16-bit bus)
Using the copy_to_user function in this driver, the data that is read from fpga is a mistake.
However, read is successful when I copy by 2byte(16-bit).

I thought copy_to_user is 32-bit access only.

  • 0
    Guru 316760 points

    copy_to_user does not have any defined access type; like memcpy, it can use whatever transfers it likes.

    If your hardware supports only 16-bit accesses, then you must copy the data to your own buffer in 'real' memory with explicit 16-bit accesses, and call copy_to_user on that.