Re: verify_area(...) possible problem.
Denis Gerasimov (denis@datawire.com)
Wed, 28 Apr 1999 17:04:02 -0400 (EDT)
On Mon, 12 Apr 1999, Linus Torvalds wrote:
....
> Basically, you should always use a kernel-space buffer. Just accept that
> as a fundamental notion, and your life suddenly turns a lot easier.
>
> Now, I know about zero-copy. I'm not a big believer in it, but I certainly
> know about it. And having a kernel buffer does not imply that you can't do
> zero-copy. It just means that you can' tdo the initial copy to user space.
>
> Sounds contradictory? Think "mmap()". It works, it's there, and magically
> all the problems go away. Don't make the mountain go to Mohammed. Instead,
> think of your problem the other way around: instead of the kernel writing
> to user space, think of it as user space asking to see a window of a
> kernel buffer. You make a device driver that has a mmap() function, and
> suddenly the device driver can write to kernel memory, and whatever it
> writes magically shows up in user space too.
Can some kind soul point me in the right direction here? I mean a code
example or a page which describes this in detail. Basically I need to have
a buffer shared between a kernel space and user space.
Thanks!
Dennis Gerasimov
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