Copying kernel module error messages to userspace

["Leonidas ." <leonidas137@xxxxxxxxx>]

Hi List

I have written a kernel module which implements a char device. An userspace app
is supposed to get data from my module and then dump it into a file for further processing.

The kind of data which kernel module is going to pass to userspace is going to be a 4K buffer,
and the data traffic is not going to be really heavy, meaning may be a 4K buffer every 1 min or so.
I am not very sure though, but certainly not heavy traffic the way they describe for network traffic etc.

And this data needs to be logged to a file either from kernel or userspace and an userspace all will work
on that data. This data needs to be logged as soon as it arrives meaning, I might not be able to write it to
/proc since from module I can update /proc only when user actually accesses it. This data needs to be
static in nature, meaning I get one error and I write it to a file somehow and user can see it anytime.
 
I hope I have described the situation clearly. I have explored some mechanism like ioctls, mmaping the
kernel buffer etc but all these would require the user module to poll or notified somehow by kernel that
the data is available. I dont want the user module to poll.


-Leo.