Map allocated kernel memory to user space

[dudi.forum1]

Hi all,
I have a very basic question, please help

Can anyone direct me the code example of mapping allocated memory at the Kernel to user space (using dma_malloc_* or even kmalloc)

Best regards
Dudi

[umeshkmahindrakar]

Hi,


you can use copy_to_user from kernel to user
or copy_from_user from user to kernel

[gerard4143]

Try this link:

Linux-Kernel: dmaable memory in user space

Is this what your after?

[dudi.forum1]

Thank you, gerard4143.
actually it answer partly to my question (the code at the link is a question by itself and has a bug) I need a code which is working the way that allocating coherent of dma'ble memory is done at the kernel and mmap to user space with no bugs. (the user space is only ask for the amout of the memory by bytes and the kernel allocate it inside the kernel)

[gerard4143]

So your trying to allocate kernel memory and have it available to user processes by mapping it into the user process...i.e. your trying to share memory freely between the kernel and user processes...is this close to what you want...Gerard4143

[dudi.forum1]

Hi gerard4143,

That's right I'm trying to get COHERENT physical memory allocated at the Kernel since the hardware I use need it. Yet it is not important to me to share is not important, I only run on user space process to access this memory