Re: Changes in vm_operations_struct 2.2.x => 2.4.x

[Martin Maletinsky <maletinsky@scs.ch>]

Hi Thomas,

The full story is, that the memory block will not only be accessed by the user space process mapping it, but also by a hardware device, which relies on the memory block
being physically contiguous (which can not be guaranteed - and will in general not be the case - for IPC shared memory). I.e. that memory block will be used to communicate
data between a user process and a hardware device.

regards
Martin

Thomas Hofer wrote:

> Martin Maletinsky wrote (Donnerstag,  9. August 2001 09:02):
> > My module allocates a block of memory, and exports that block to user
> > space processes, by registering as a character device and
> > implementing a mmap file operation, so that user space processes can
> > map that memory block into their virtual address space by calling
> > mmap().
>
> Would it be possible to do this with shared memory (shmget/shmat)?
> What's the advantage of making a device and mmaping it? Sounds
> more complicated. (I did only user-space programs as yet, so forgive me
> my naivity)
>
> Thomas.
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