user-to-kernel shared memory with net_device

user-to-kernel shared memory with net_device

[Chris Ross]

I have a net_device driver that has a fairly large (1-2MB) set of
stats that a user space process needs to read from time to time. I had
assumed the optimal ipc mechanism would be shared memory. Now that I'm
getting around to implementation of this side of the project I'm
getting a bit stuck.

All of the mmap examples I can find seem to be for character devices.
Do I need a character device that implements mmap and proxies access
to the net_device's stats, or is there a way to mmap directly to a
net_device structure? Also, is this the excepted method when a
userspace process needs to read large tables from a driver?

thanks,

-chris

Re: user-to-kernel shared memory with net_device

[Rémi Denis-Courmont]

On Mon, 19 Oct 2009 16:28:42 -0500, Chris Ross <chris@compilednetworks.com>
wrote:
> All of the mmap examples I can find seem to be for character devices.
> Do I need a character device that implements mmap and proxies access
> to the net_device's stats, or is there a way to mmap directly to a
> net_device structure? Also, is this the excepted method when a
> userspace process needs to read large tables from a driver?

You cannot use mmap() directly on a network device as there are no file
descriptors to network devices. In principle, you can still initiate a
memory mapping using a network device ioctl(), but this is probably not
such a great idea.

-- 
Rémi Denis-Courmont