mmap maped memory trace

mmap maped memory trace

[Nikola Gidalov]

Dear kernel experts,

I'd like to ask you how it is possible to to be notified in the driver
module whenever the user of driver writes to the mmap-ed memory from
the driver.

I'm making a virtual 8bpp framebuffer driver. The user of the fb
driver uses mmap to map the framebuffer memory. In the driver I use
the vmalloc memory and map the memory to the user space when the user
calls mmap.
Now , I'd like to intercept the "memory-write" operation to my mmaped
memory, to convert the 8bpp value to 32bpp and to write the 32bpp
value to the real framebuffer on the fly.
Changing the clients to use 32bpp framebuffer directly os not an option.

With kind regards,

Nikola

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Re: mmap maped memory trace

[Andi Kleen]

On Sat, 12 Aug 2006 23:43:46 +0200
"Nikola Gidalov" <ngidalov@gmail.com> wrote:

> I'd like to ask you how it is possible to to be notified in the driver
> module whenever the user of driver writes to the mmap-ed memory from
> the driver.

You would need to unmap the area and then on a fault emulate the store instruction
and fake its behaviour.

You probably don't want to go this way, it would be fairly complicated.

-Andi

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